Otical disc apparatus

ABSTRACT

The present invention relates to an optical disk apparatus which performs information recording or reproduction into/from an optical disk, and provides an optical disk apparatus which makes the amount of optical pickup movement performed before adjustment of a track error signal suited and enables reduction of a start-up time.  
     When a track error signal is subjected to adjustment, it is previously detected in a signal amplitude detecting circuit  17  whether an optical pickup  1  is located in an area where a required track on an optical disk medium  2  exists or not, and a micro processing unit  6  executes the procedure which uses only the necessary but minimum moving time, even when the optical pickup is required to be moved.

TECHNICAL FIELD

[0001] The present invention relates to an optical disk apparatus whichperforms recording or reproduction of information into/from an opticaldisk and, more particularly, to one which can perform adjustment of atrack error signal reliably and effectively thereby to shorten astart-up time at starting this apparatus into which an optical diskmedium is installed.

BACKGROUND ART

[0002] Hereinafter, a conventional optical disk apparatus will bedescribed.

[0003]FIG. 14 is a block diagram illustrating a constitution of theconventional optical disk apparatus.

[0004] In FIG. 14, numeral 2 denotes an optical disk medium such as aCD, a CD-ROM, a DVD, and an MO, which has a track for informationrecording, and numeral 1 denotes an optical pickup which collects asemiconductor laser to irradiate the light to a target position on theoptical disk medium 2, thereby to perform recording and reproduction ofinformation, and this comprises an optical system and a driving system.The optical system collects a laser beam on the surface of the opticaldisk medium 2 or detects a deviation between a irradiated position of alaser beam and a target position on the optical disk medium 2, and itcomprises a semiconductor laser, lenses, a beam splitter, a photodiodeor the like (all not shown). On the other hand, the driving system isdriven to perform a focus control which makes an objective lens followplane wobbles on the optical disk medium 2 or a tracking control whichmakes the F objective lens follow track wobbles, and keeps thepositional relationship between the target position on the optical diskmedium 2 and a laser beam spot constant, and it mainly comprises amagnet, a coil, and a support member (all not shown). The driving systemserves as an actuator which drives the lenses of the optical system.

[0005] Numeral 3 denotes an operational amplifier which performs variousarithmetic processings to a returned light quantity signal from theoptical disk medium 2 which returned light is detected by photodiodeswhich are divided into plural parts, which photodiodes construct theoptical pickup 1, and it outputs a focus error signal (hereinafter,referred to as FE signal) presenting a focus deviation quantity of thelaser beam spot on the optical disk medium 2, a track error signal(hereinafter, referred to as TE signal) presenting a positionaldeviation amount of the laser beam spot with relative to a track on theoptical disk medium 2, and a reproduction signal (hereinafter, referredto as RF signal) presenting information recorded as a change in lightreflectance on the optical disk medium 2. Numeral 4 denotes a focuscontrol circuit which performs a focus control of collecting the laserbeam irradiated from the optical pickup 1 to focus the same on theoptical disk medium 2, numeral 5 denotes a focus driving circuit whichis controlled by the focus control circuit 4 and drives an actuator ofan objective lens of the optical pickup 1, and numeral 6 denotes a microprocessing unit (hereinafter, referred to as MPU) presenting anarithmetic processing unit, and by a command of this MPU 6, ON/OFF ofthe above-mentioned focus control operation is operated. Numeral 7denotes an adjusting circuit which comprises an offset control circuit71 and a variable gain amplifier 72, and receives the TE signaloutputted from the operational amplifier 3, adjusts a gain and an offsetby settings from the MPU 6, and outputs a track error signal afteradjustment (hereinafter, referred to as a TEA signal), numeral 8 denotesa tracking control circuit which receives the TEA signal and performs acontrol so that the irradiated position of the laser beam follows thetrack of the optical disk medium 2, and numeral 9 denotes a trackingdriving circuit which drives the objective lens of the optical pickup 1with controlled by the tracking control circuit 8, and ON/OFF of thistracking control operation is operated by a command of the MPU 6.

[0006] Numeral 10 denotes a traverse control circuit which receives acontrol output signal (hereinafter, referred to as TRO signal) outputtedfrom the tracking control circuit 8, and generates a TVO signalpresenting a control signal for moving the optical pickup 1 itself tofollow in a radial direction of the optical disk 2 when the irradiatedposition of the laser beam of the optical pickup 1 follows the spiraltrack on the optical disk medium 2, numeral 11 denotes a traversedriving circuit which receives the TVO signal and drives anafter-mentioned traverse motor 12, and numeral 12 denotes a traversemotor which moves the optical pickup 1 in a radial direction of theoptical disk medium 2. Further, numeral 13 denotes a signal processingcircuit which receives the RF signal outputted from the operationalamplifier 3, and reproduces information from the optical disk medium 2,and it extracts a SYNC signal presenting a synchronization signal fromthe RF signal. Numeral 14 denotes a spindle motor control circuit whichreceives the SYNC signal extracted from the signal processing circuit 13and outputs a DMO signal for controlling the rotation number of theoptical disk medium 2, numeral 15 denotes a spindle motor drivingcircuit which receives the DMO signal from the spindle motor controlcircuit 14 and drives an after-mentioned spindle motor, and numeral 16denotes a spindle motor for rotating the optical disk medium 2, and therotation of the spindle motor 16 can be also controlled at a prescribedrotation number by inputting an FG signal indicating a rotation numberto the spindle motor control circuit 14, not by the SYNC signal.

[0007] Next, an adjusting operation of the track error signal, which isperformed when the conventional optical disk apparatus on which theoptical disk medium 2 is mounted is started will be described withreference to the flow chart in FIG. 15.

[0008] When the optical disk medium 2 is mounted on the optical diskapparatus or the power is turned ON (Step S901), the MPU 6 initializesthe position of the optical pickup 1 (Step S902). More specifically, thetraverse motor 12 is driven so as to move the optical pickup 1 forciblyto the inner periphery side of the optical disk medium 2 until aninnermost periphery switch (not shown) is pressed (Step S903). Whenthere is no innermost periphery switch, the traverse motor 12 is keptdriven while the optical pickup 1 is surely moved to a limit of themovable range in which the optical pickup 1 can move to the innerperiphery side. After the optical pickup 1 is moved to the innermostperiphery position of the optical disk medium 2 in this way, the opticalpickup 1 is moved to the outer periphery side for a prescribed time soas to be located at a position where the track on the optical diskmedium 2 exists (Step S904).

[0009]FIG. 16 illustrates an area structure of the optical disk medium,such as a general compact disk (hereinafter, referred to as a CD), arecordable CD-R, or a rewritable CD-RW, in a radial direction. As shownin FIG. 16, the innermost periphery part is a clamp area A1 for mountingthe disk, and an information area A2 where a track exists exists outsidethe clamp area. In the inner periphery and outer periphery of theinformation area A2, there exist mirror surface areas A30 and A31 inwhich a reflecting layer is formed but no tracks exist and substrateareas A40 and A41 made only of transparent substrates. Therefore, theoptical pickup 1 is located in the information area A2 of the opticaldisk medium 2 by the above-described operation of initializing theposition of the optical pickup 1.

[0010] Next, a returned light quantity from the optical disk medium 2when an objective lens of the optical pickup 1 is operated up and downin a focus direction is detected from the level of the RF signal, andthe presence or absence of the disk is judged (Step S905). At that time,it is utilized that a prescribed RF signal level can be obtained whenthe optical disk medium 2 is actually mounted on the optical diskapparatus. As the result of the judgement, when the optical disk medium2 is judged to be mounted, the spindle motor 16 is driven to rotate theoptical disk medium 2 (Step S906), and the focus control of the opticalpickup 1 is turned ON (Step S907).

[0011] The collected laser beam spot crosses the track on the opticaldisk medium 2 due to eccentricity of the optical disk medium 2 itself orthe deviation of the center at mounting or the like. This state isreferred to as track cross state. While the TE signal at the track crossstate is of an almost sine wave form as shown in FIG. 17, its signalamplitude or signal offset may be changed due to difference inreflectance of the optical disk medium 2, difference in sensitivity ofthe photodiode, asymmetry of groove shape in the track, or the like.Then, the TE signal has its gain and offset adjusted by the offsetadjusting circuit 71 and the variable gain amplifier 72 that constructthe adjusting circuit 7 based on setting from the MPU 6, so that the TEAsignal presenting a track error signal after adjustment as shown in FIG.17 is generated (Step S908). The track error signal is subjected toadjustment in this way, whereby a control operation can be performed sothat the laser beam spot of the optical pickup 1 performs trackingaccurately in the center of the track on the optical disk medium 2.

[0012] When the tracking control is prepared to be operated accuratelyby the above-described adjustment of the track error signal, thetracking control is turned ON (Step S909), and a traverse followingcontrol is subsequently turned ON so that the laser beam spot of theoptical pickup 1 follows the spiral track on the optical disk medium 2(Step S910).

[0013] In this way, the laser beam spot of the optical pickup 1 canaccurately follow the track on the optical disk medium 2, wherebyinformation in the optical disk medium 2 can be reproduced (Step S911),and the start-up of the optical disk apparatus is completed.

[0014] The so-constructed conventional optical disk apparatus transfersthe optical pickup in a radial direction of the optical disk medium at aprescribed speed with the position of the objective lens of the opticalpickup held, and almost prescribed track cross frequency is obtained,thereby to enhance adjustment accuracy of the amplitude and offset ofthe track error signal.

[0015] However, the above-described conventional optical disk apparatushave the following problem.

[0016] That is, the conventional optical disk apparatus is required toinitialize the position of the optical pickup 1 before adjusting thetrack error signal, and to move the optical pickup 1 to the initializedposition in several seconds so as to move the optical pickup 1 with noimpulse added or no noise generated when moving the same to theinnermost periphery position.

[0017] Therefore, the optical pickup 1 needs to be subjected to themoving operation to the initialized position though its position atstart-up is within the information area where the track on the opticaldisk medium 2 exists, excepting such a specific situation where anabnormal operation termination is generated as a case where the opticalpickup 1 is in runaway state and the power is turned OFF, whereby astart-up time of the optical disk apparatus until information from theoptical disk medium 2 is read to be recorded/reproduced becomes longer.

[0018] The present invention is made to solve the above-mentionedproblem and has for its object to obtain an optical disk apparatus whichperforms adjustment of a track error signal accurately and effectively,thereby to shorten a start-up time.

DISCLOSURE OF THE INVENTION

[0019] To solve the above-described problem, an optical disk apparatusaccording to claim 1 of the present invention comprising: an opticalpickup which performs recording or reproduction of information into/froman optical disk medium having a track for information recording; a focuscontrol means for controlling the optical pickup so as to focus a lightbeam on the optical disk medium; a tracking actuator which drives theoptical pickup so that an irradiated position of the light beam followsthe track for information recording; a track error detecting means fordetecting a deviation from the track position of the irradiated positionof the light beam; an adjusting means for adjusting gain and offset of atrack error signal outputted by the track error detecting means; and atracking driving means for driving the tracking actuator according to anoutput signal of the adjusting means, comprises: an amplitude detectingmeans for detecting amplitude of the track error signal; and a transfermeans for transferring the optical pickup in a radial direction of theoptical disk medium, and the focus control means focuses the light beamirradiated from the optical pickup onto the optical disk medium, and theadjusting means adjusts the gain and offset of the track error signalwhen the amplitude of the track error signal detected by the amplitudedetecting means is equal to or larger than a previously set value, whilethe optical pickup is transferred to a previously decided position whenthe amplitude of the track error signal detected by the amplitudedetecting means is under the previously set value.

[0020] According to the present invention, shift of the optical pickupto the initialized position at start-up can be almost eliminated,resulting in drastic reduction of a startup time.

[0021] According to claim 2 of the present invention, an optical diskapparatus comprising: an optical pickup which performs recording orreproduction of information into/from an optical disk medium having atrack for information recording; a focus control means for controllingthe optical pickup so as to focus a light beam on the optical diskmedium; a tracking actuator which drives the optical pickup so that anirradiated position of the light beam follows the track for informationrecording; a track error detecting means for detecting a deviation fromthe track position of the irradiated position of the light beam; anadjusting means for adjusting gain and offset of a track error signaloutputted by the track error detecting means; and a tracking drivingmeans for driving the tracking actuator according to an output signal ofthe adjusting means, comprises: an amplitude detecting means fordetecting amplitude of the track error signal; an objective lens shiftmeans for providing a signal to the tracking driving means to shift anobjective lens of the optical pickup in a radial direction of theoptical disk medium; and a transfer means for transferring the opticalpickup in the radial direction of the optical disk medium, and the focuscontrol means focuses the light beam irradiated from the optical pickuponto the optical disk medium, and according to a first comparison resultwhich is obtained by comparing amplitude of a first track error signaldetected in the amplitude detecting means with a previously set value ina state where the objective lens of the optical pickup is shifted in anouter periphery direction of the optical disk medium by the objectivelens shift means, as well as a second comparison result which isobtained by comparing amplitude of a second track error signal detectedin the amplitude detecting means with the previously set value in astate where the objective lens of the optical pickup is shifted in aninner periphery direction of the optical disk medium by the objectivelens shift means, the gain and offset of the track error signal areadjusted when the first and the second comparison results are both equalto or larger than the previously set value; the optical pickup istransferred in the outer periphery direction of the optical disk mediumwhen the first comparison result is equal to or larger than thepreviously set value and the second comparison result is under thepreviously set value; the optical pickup is transferred in the innerperiphery direction of the optical disk medium when the first comparisonresult is under the previously set value and the second comparisonresult is equal to or larger than the previously set value; and theoptical pickup is transferred to a previously decided position when thefirst and the second comparison results are both under the previouslyset value.

[0022] According to the present invention, it is decided whether theoptical pickup needs to be moved before the adjusting operation of thetrack error signal is performed, and the optical pickup can be moved tothe most appropriate direction also when the movement is judged to berequired, whereby the movement of the optical pickup can be optimizedeven when the optical pickup is located at a boundary of the area wherethe track on the optical disk medium exists at startup, resulting indrastic reduction of a startup time.

[0023] According to claim 3 of the present invention, an optical diskapparatus comprising: an optical pickup which performs recording orreproduction of information into/from an optical disk medium having atrack for information recording; a focus control means for controllingthe optical pickup so as to focus a light beam on the optical diskmedium; a tracking actuator which drives the optical pickup so that anirradiated position of the light beam follows the track for informationrecording; a track error detecting means for detecting a deviation fromthe track position of the irradiated position of the light beam; anadjusting means for adjusting gain and offset of a track error signaloutputted by the track error detecting means; and a tracking drivingmeans for driving the tracking actuator according to an output signal ofthe adjusting means, comprises: an amplitude detecting means fordetecting amplitude of the track error signal; an objective lens shiftmeans for providing a signal to the tracking driving means to shift anobjective lens of the optical pickup in a radial direction of theoptical disk medium; and a transfer means for transferring the opticalpickup in the radial direction of the optical disk medium, and thetransfer means transfers the optical pickup in an outer peripherydirection of the optical disk medium, the focus control means focusesthe light beam irradiated from the optical pickup onto the optical diskmedium, and shift of the objective lens is stopped and the adjustingmeans adjusts the gain and offset of the track error signal when theamplitude of the track error signal detected by the amplitude detectingmeans is equal to or larger than a previously set value in a state wherethe objective lens of the optical pickup is shifted in the outerperiphery direction of the optical disk medium by the objective lensshift means, while the optical pickup is transferred in an innerperiphery direction of the optical disk medium when the amplitude of thetrack error signal detected by the amplitude detecting means is underthe previously set value.

[0024] According to the present invention, the amount of the opticalpickup moving at startup can be drastically decreased, resulting indrastic reduction of a startup time.

[0025] According to claim 4 of the present invention, an optical diskapparatus comprising: an optical pickup which performs recording orreproduction of information into/from an optical disk medium having atrack for information recording; a focus control means for controllingthe optical pickup so as to focus a light beam on the optical diskmedium; a tracking actuator which drives the optical pickup so that anirradiated position of the light beam follows the track for informationrecording; a track error detecting means for detecting a deviation fromthe track position of the irradiated position of the light beam; anadjusting means for adjusting gain and offset of a track error signaloutputted by the track error detecting means; and a tracking drivingmeans for driving the tracking actuator according to an output signal ofthe adjusting means, comprises: an amplitude detecting means fordetecting amplitude of the track error signal; an objective lens shiftmeans for providing a signal to the tracking driving means to shift anobjective lens of the optical pickup in a radial direction of theoptical disk medium; and a transfer means for transferring the opticalpickup in the radial direction of the optical disk medium, and thetransfer means transfers the optical pickup in an inner peripherydirection of the optical disk medium, the focus control means focusesthe light beam irradiated from the optical pickup onto the optical diskmedium, and shift of the objective lens is stopped and the gain andoffset of the track error signal are adjusted by the adjusting meanswhen the amplitude of the track error signal detected by the amplitudedetecting means is equal to or larger than a previously set value in astate where the objective lens shift means shifts the objective lens ofthe optical pickup in the inner periphery direction of the optical diskmedium, while the optical pickup is transferred in an inner peripherydirection of the optical disk medium when the amplitude of the trackerror signal detected by the amplitude detecting means is under thepreviously set value.

[0026] According to the present invention, the amount of the opticalpickup moving at startup can be drastically decreased, resulting indrastic reduction of a startup time.

[0027] According to claim 5 of the present invention, in the opticaldisk apparatus as defined in any of claims 1 to 4, the amplitude of thetrack error signal is detected by the amplitude detecting means for aperiod of one rotation or more in synchronization with the rotation ofthe optical disk medium.

[0028] According to the present invention, amplitude of the track errorsignal can be certainly detected even when the status of the track errorsignal is changed due to eccentricity of the optical disk medium itself,the deviation of the center at mounting, vibration of the objective lensof the optical pickup, or the like.

[0029] According to claim 6 of the present invention, an optical diskapparatus comprising: an optical pickup which performs recording orreproduction of information into/from an optical disk medium having atrack for information recording; a focus control means for controllingthe optical pickup so as to focus a light beam on the optical diskmedium; a tracking actuator which drives the optical pickup so that anirradiated position of the light beam follows the track for informationrecording; a track error detecting means for detecting a deviation fromthe track position of the irradiated position of the light beam; anadjusting means for adjusting gain and offset of a track error signaloutputted by the track error detecting means; and a tracking drivingmeans for driving the tracking actuator according to an output signal ofthe adjusting means, comprises: a returned light quantity detectingmeans for detecting a returned light quantity from the optical diskmedium; an amplitude detecting means for detecting amplitude of anoutput signal of the returned light quantity detecting means; and atransfer means for transferring the optical pickup in a radial directionof the optical disk medium, and the focus control means focuses thelight beam from the optical pickup onto the optical disk medium, and theadjusting means adjusts the gain and offset of the track error signalwhen the amplitude of the returned light quantity signal detected by theamplitude detecting means is equal to or larger than a previously setvalue, while the optical pickup is transferred to a previously decidedposition when the amplitude of the returned light quantity signaldetected by the amplitude detecting means is under the previously setvalue.

[0030] According to the present invention, shift of the optical pickupto the initialized position at start-up can be almost eliminated,resulting in drastic reduction of a startup time.

[0031] According to claim 7 of the present invention, an optical diskapparatus comprising: an optical pickup which performs recording orreproduction of information into/from an optical disk medium having atrack for information recording; a focus control means for controllingthe optical pickup so as to focus a light beam on the optical diskmedium; a tracking actuator which drives the optical pickup so that anirradiated position of the light beam follows the track for informationrecording; a track error detecting means for detecting a deviation fromthe track position of the irradiated position of the light beam; anadjusting means for adjusting gain and offset of a track error signaloutputted by the track error detecting means; and a tracking drivingmeans for driving the tracking actuator according to an output signal ofthe adjusting means, comprises: a returned light quantity detectingmeans for detecting a returned light quantity from the optical diskmedium; an amplitude detecting means for detecting amplitude of anoutput signal of the returned light quantity detecting means; anobjective lens shift means for providing a signal to the trackingdriving means to shift an objective lens of the optical pickup in aradial direction of the optical disk medium; and a transfer means fortransferring the optical pickup in the radial direction of the opticaldisk medium, and the focus control means focuses the light beamirradiated from the optical pickup onto the optical disk medium, andaccording to a first comparison result which is obtained by comparingamplitude of a first returned light quantity signal detected in theamplitude detecting means with a previously set value in a state wherethe objective lens of the optical pickup is shifted in an outerperiphery direction of the optical disk medium by the objective lensshift means, as well as a second comparison result which is obtained bycomparing amplitude of a second returned light quantity signal detectedin the amplitude detecting means with the previously set value in astate where the objective lens of the optical pickup is shifted in aninner periphery direction of the optical disk medium by the objectivelens shift means, the gain and offset of the track error signal areadjusted when the first and the second comparison results are both equalto or larger than the previously set value; the optical pickup istransferred in the outer periphery direction of the optical disk mediumwhen the first comparison result is equal to or larger than thepreviously set value and the second comparison result is under thepreviously set value; the optical pickup is transferred in the innerperiphery direction of the optical disk medium when the first comparisonresult is under the previously set value and the second comparisonresult is equal to or larger than the previously set value; and theoptical pickup is transferred to a previously decided position when thefirst and the second comparison results are both under the previouslyset value.

[0032] According to the present invention, it is decided whether theoptical pickup needs to be moved before the adjusting operation of thetrack error signal is performed, and the optical pickup can be moved tothe most appropriate direction also when the movement is judged to berequired, whereby the movement of the optical pickup can be optimizedeven when the optical pickup is located at a boundary of the area wherethe track on the optical disk medium exists at startup, resulting indrastic reduction of a startup time.

[0033] According to claim 8 of the present invention, an optical diskapparatus comprising: an optical pickup which performs recording orreproduction of information into/from an optical disk medium having atrack for information recording; a focus control means for controllingthe optical pickup so as to focus a light beam on the optical diskmedium; a tracking actuator which drives the optical pickup so that anirradiated position of the light beam follows the track for informationrecording; a track error detecting means for detecting a deviation fromthe track position of the irradiated position of the light beam; anadjusting means for adjusting gain and offset of a track error signaloutputted by the track error detecting means; and a tracking drivingmeans for driving the tracking actuator according to an output signal ofthe adjusting means, comprises: a returned light quantity detectingmeans for detecting a returned light quantity from the optical diskmedium; an amplitude detecting means for detecting amplitude of anoutput signal of the returned light quantity detecting means; anobjective lens shift means for providing a signal to the trackingdriving means to shift an objective lens of the optical pickup in aradial direction of the optical disk medium; and a transfer means fortransferring the optical pickup in the radial direction of the opticaldisk medium, and the transfer means transfers the optical pickup in anouter periphery direction of the optical disk medium, the focus controlmeans focuses the light beam from the optical pickup onto the opticaldisk medium, and shift of the objective lens is stopped and the gain andoffset of the track error signal are adjusted by the adjusting meanswhen the amplitude of the returned light quantity signal detected by theamplitude detecting means is equal to or larger than a previously setvalue in a state where the objective lens of the optical pickup isshifted in the outer periphery direction of the optical disk medium bythe objective lens shift means, while the optical pickup is transferredin an inner periphery direction of the optical disk medium when theamplitude of the returned light quantity signal detected by theamplitude detecting means is under the previously set value.

[0034] According to the present invention, the amount of the opticalpickup moving at startup can be drastically decreased, resulting indrastic reduction of a startup time.

[0035] According to claim 9 of the present invention, an optical diskapparatus comprising: an optical pickup which performs recording orreproduction of information into/from an optical disk medium having atrack for information recording; a focus control means for controllingthe optical pickup so as to focus a light beam on the optical diskmedium; a tracking actuator which drives the optical pickup so that anirradiated position of the light beam follows the track for informationrecording; a track error detecting means for detecting a deviation fromthe track position of the irradiated position of the light beam; anadjusting means for adjusting gain and offset of a track error signaloutputted by the track error detecting means; and a tracking drivingmeans for driving the tracking actuator according to an output signal ofthe adjusting means, comprises: a returned light quantity detectingmeans for detecting a returned light quantity from the optical diskmedium; an amplitude detecting means for detecting amplitude of anoutput signal of the returned light quantity detecting means; anobjective lens shift means for providing a signal to the trackingdriving means to shift an objective lens of the optical pickup in aradial direction of the optical disk medium; and a transfer means fortransferring the optical pickup in the radial direction of the opticaldisk medium, and the transfer means transfers the optical pickup in aninner periphery direction of the optical disk medium, the light beamirradiated from the optical pickup is focused onto the optical diskmedium by the focus control means, and shift of the objective lens isstopped and the gain and offset of the track error signal are adjustedby the adjusting means when the amplitude of the returned light quantitysignal detected by the amplitude detecting means is equal to or largerthan a previously set value in a state where the objective lens of theoptical pickup is shifted in the inner periphery direction of theoptical disk medium by the objective lens shift means, while the opticalpickup is transferred in an outer periphery direction of the opticaldisk medium when the amplitude of the returned light quantity signaldetected by the amplitude detecting means is under the previously setvalue.

[0036] According to the present invention, the amount of the opticalpickup moving at startup can be drastically decreased, resulting indrastic reduction of a startup time.

[0037] According to claim 10 of the present invention, in the opticaldisk apparatus as defined in any of claims 6 to 9, the amplitude of thereturned light quantity signal is detected by the amplitude detectingmeans for a period of one rotation or more in synchronization with therotation of the optical disc medium.

[0038] According to the present invention, amplitude of the track errorsignal can be certainly detected even when the status of the returnedlight quantity signal is changed due to eccentricity of the optical diskmedium itself, the deviation of the center at mounting, vibration of theobjective lens of the optical pickup, or the like.

BRIEF DESCRIPTION OF DRAWINGS

[0039]FIG. 1 is a block diagram illustrating a constitution of anoptical disk apparatus according to a first embodiment of the presentinvention.

[0040]FIG. 2 is a flow chart for explaining the operation of the opticaldisk apparatus according to the first embodiment of the presentinvention.

[0041]FIG. 3 is a block diagram illustrating a constitution of anoptical disk apparatus according to a second to a fourth embodiments ofthe present invention.

[0042]FIG. 4 is a flow chart for explaining the operation of the opticaldisk apparatus according to the second embodiment of the presentinvention.

[0043]FIG. 5 is a flow chart for explaining the operation of the opticaldisk apparatus according to the third embodiment of the presentinvention.

[0044]FIG. 6 is a flow chart for explaining the operation of the opticaldisk apparatus according to the fourth embodiment of the presentinvention.

[0045]FIG. 7 is a block diagram illustrating a constitution of anoptical disk apparatus according to a sixth embodiment of the presentinvention.

[0046]FIG. 8 is a flow chart for explaining the operation of the opticaldisk apparatus according to the sixth embodiment of the presentinvention.

[0047]FIG. 9 is a diagram illustrating an RF signal and TE signal of arecorded part and unrecorded part in track cross state.

[0048]FIG. 10 is a block diagram illustrating a constitution of anoptical disk apparatus according to a seventh to a ninth embodiments ofthe present invention.

[0049]FIG. 11 is a flow chart for explaining the operation of theoptical disk apparatus according to the seventh embodiment of thepresent invention.

[0050]FIG. 12 is a flow chart for explaining the operation of theoptical disk apparatus according to the eighth embodiment of the presentinvention.

[0051]FIG. 13 is a flow chart for explaining the operation of theoptical disk apparatus according to a ninth embodiment of the presentinvention.

[0052]FIG. 14 is a block diagram illustrating a constitution of aconventional optical disk apparatus.

[0053]FIG. 15 is a flow chart for explaining the operation of theconventional optical disk apparatus.

[0054]FIG. 16 is a diagram illustrating a constitution of an area in anoptical disk medium.

[0055]FIG. 17 is a diagram illustrating a TE signal and TEA signal intrack cross state.

BEST MODE TO EXECUTE THE INVENTION

[0056] Hereinafter, embodiments of the present invention will bedescribed with reference to figures.

EMBODIMENT 1

[0057]FIG. 1 is a block diagram illustrating a constitution of anoptical disk apparatus according to a first embodiment of the presentinvention.

[0058] In FIG. 1, numeral 2 denotes an optical disk medium such as a CD,a CD-ROM, a DVD, and an MO, which has a track for information recording,and numeral 1 denoted an optical pickup which collects a semiconductorlaser to irradiate the light to a target position on the optical diskmedium 2, thereby to perform recording or reproduction of information,and this comprises an optical system and a driving system. The opticalsystem collects a laser beam on the surface of the optical disk medium 2or detects a deviation between a irradiated position of a laser beam anda target position on the optical disk medium 2, and it comprises asemiconductor laser, lenses, a beam splitter, a photodiode or the like(all not shown). On the other hand, the driving system is driven toperform a focus control which makes an objective lens follow planewobbles on the optical disk medium 2 or a tracking control which makesthe objective lens follow track wobbles, and keeps the positionalrelationship between the target position on the optical disk medium 2and a laser beam spot constant, and it mainly comprises a magnet, acoil, and a support member (all not shown). The driving system serves asan actuator which drives the lenses of the optical system.

[0059] Numeral 3 denotes an operational amplifier (track error detectingmeans) which performs various arithmetic processings to a returned lightquantity signal from the optical disk medium 2 which returned light isdetected by photodiodes which are divided into plural parts, whichphotodiodes construct the optical pickup 1, and it outputs a focus errorsignal (hereinafter, referred to as FE signal) presenting a focusdeviation quantity of the laser beam spot on the optical disk medium 2,a track error signal (hereinafter, referred to as TE signal) presentinga positional deviation amount of the laser beam spot with relative to atrack on the optical disk medium 2, and a reproduction signal(hereinafter, referred to as RF signal) presenting information recordedas a change in light reflectance on the optical disk medium 2. Numeral 4denotes a focus control circuit (focus control means) which performs afocus control of collecting the laser beam irradiated from the opticalpickup 1 to focus the same on the optical disk medium 2, numeral 5denotes a focus driving circuit which is controlled by the focus controlcircuit 4 and drives an actuator of an objective lens of the opticalpickup 1, and numeral 6 denotes a micro processing unit (hereinafter,referred to as MPU) presenting an arithmetic processing unit, by acommand of MPU 6, ON/OFF of the above-mentioned focus control operationis operated. Numeral 7 denotes an adjusting circuit (adjusting means)which comprises an offset control circuit 71 and a variable gainamplifier 72, and receives the TE signal outputted from the operationalamplifier 3, adjusts a gain and an offset by settings from the MPU 6,and outputs a track error signal after adjustment (hereinafter, referredto as a TEA signal), numeral 8 denotes a tracking control circuit whichreceives the TEA signal and performs a control so that the irradiatedposition of the laser beam follows the track of the optical disk medium2, and numeral 9 denotes a tracking driving circuit (tracking drivingmeans) which drives the actuator of the objective lens of the opticalpickup 1 with controlled by the tracking control circuit 8, and ON/OFFof this tracking control operation is operated by a command of the MPU6.

[0060] Numeral 10 denotes a traverse control circuit which receives acontrol output signal (hereinafter, referred to as TRO signal) outputtedfrom the tracking control circuit 8, and generates a TVO signalpresenting a control signal for moving the optical pickup 1 itself tofollow in a radial direction of the optical disk 2 when the irradiatedposition of the laser beam of the optical pickup 1 follows the spiraltrack on the optical disk medium 2, numeral 11 denotes a traversedriving circuit which receives the TVO signal and drives anafter-mentioned traverse motor 12, and numeral 12 denotes a traversemotor (transfer means) which moves the optical pickup 1 in a radialdirection of the optical disk medium 2. Further, numeral 13 denotes asignal processing circuit which receives the RF signal outputted fromthe operational amplifier 3, and reproduces information from the opticaldisk medium 2, and it extracts a SYNC signal presenting asynchronization signal from the RF signal. Numeral 14 denotes a spindlemotor control circuit which receives the SYNC signal extracted from thesignal processing circuit 13 and outputs a DMO signal for controllingthe rotation number of the optical disk medium 2, numeral 15 denotes aspindle motor driving circuit which receives the DMO signal from thespindle motor control circuit 14 and drives an after-mentioned spindlemotor, and numeral 16 denotes a spindle motor for rotating the opticaldisk medium 2, and the rotation of the spindle motor 16 can be alsocontrolled at a prescribed rotation number by inputting an FG signalindicating a rotation number to the spindle motor control circuit 14,not by the SYNC signal. Numeral 17 denotes a signal amplitude detectingcircuit (amplitude detecting means) as a means for detecting amplitudeof the TE signal before adjustment, which outputs an output signal TEpp.Further, the signal amplitude detecting circuit 17 comprises a peak holdcircuit, a bottom hold circuit, and a differential amplifier (all notshown). Numeral 18 denotes a comparator which compares the level of theoutput signal TEpp outputted from the signal amplitude detecting circuit17 with a prescribed level signal TEref set by the MPU 6, and has itsoutput signal Sig1 inputted to the MPU 6.

[0061] A collected laser beam spot crosses the track on the optical diskmedium 2 due to eccentricity of the optical disk medium 2 or thedeviation of the center at mounting or the like. This state is referredto as track cross state, and the TE signal in the track cross state isdescribed in FIG. 17(a). The level indicated by the TEpp is theabove-described output signal outputted in the signal amplitudedetecting circuit 17.

[0062] From FIG. 17(a), the TE signal is of an almost sine wave form,while its signal amplitude or signal offset may be changed due todifference in reflectance of the optical disk medium 2, difference insensitivity of the photodiode, asymmetry of groove shape in the track,or the like. Then, the TE signal has its gain and offset adjusted by theoffset adjusting circuit 71 and the variable gain amplifier 72 thatconstruct the adjusting circuit 7 based on setting from the MPU 6 .

[0063]FIG. 17(b) illustrates the TEA signal presenting a track errorsignal after adjustment.

[0064] Next, the operation of the optical disk apparatus according tothe first embodiment will be described.

[0065]FIG. 2 is a flow chart for explaining the operation of the opticaldisk apparatus according to the first embodiment of the presentinvention.

[0066]FIG. 16 is a diagram of an area construction of an optical diskmedium in a radial direction. In FIG. 16, an innermost periphery part Aldenotes a clamp area for mounting the disk, A2 denotes an informationarea where a track exists, A30 and A31 denote mirror surface areas whereno tracks exist, and A40 and A41 denote substrate areas made only oftransparent substrates.

[0067] When the optical disk medium 2 is mounted on the optical diskapparatus or the power of the optical disk apparatus is turned ON (StepS101), a judgement whether the optical disk medium 2 is in the opticaldisk apparatus or not is performed (Step 5102). Here, the followingoperation is performed to judge whether the optical disk medium 2 is inthe optical disk apparatus or not.

[0068] First, a returned light quantity from the optical disk medium 2when an objective lens of the optical pickup 1 is operated up and downin a focus direction is detected from the level of the RF signal. Whenthe optical disk medium 2 is mounted on the optical disk apparatus, aprescribed RF signal level is obtained when the optical pickup 1 islocated in the information area A2 and the mirror surface areas A30 andA31 of the optical disk medium 2 as shown in FIG. 16. However, theoptical pickup 1 before start-up can be located in an area differentfrom a usual one (area other than the information area and the mirrorsurface area), and thus, the following operation is performed inaddition to the judgement of the presence or absence of the optical diskmedium 2 by the level of the RF signal. That is, the spindle motor 16 isforcibly accelerated for a definite period of time, a change in therotation number of the spindle motor 16 is detected from the FG signal,and inertia of a rotor part of the spindle motor 16 is measured, therebyjudging the presence or absence of the optical disk medium 2. Here, whenthe optical disk medium 2 is judged not to exist according to thejudgement of the presence or absence of the disk by the RF signal, whilethe optical disk medium 2 is judged to exist according to the judgementof the presence or absence of the disk by the inertia measurement, forexample, it is an abnormal state where the optical pickup 1 beforestart-up is located in an area different from a usual one, and thus, anoperation for initializing the position of the optical pickup 1 isperformed to continue the processing. This judgement of the presence orabsence of the optical disk medium 2 is performed in Step S102.

[0069] Subsequently, when the optical disk medium 2 is judge to exist asthe result of the judgement in Step S102, the spindle motor 16 is drivento start rotating the optical disk medium 2 (Step S103), and the focuscontrol of the optical pickup 1 is turned ON (Step S104). On the otherhand, when the optical disk medium 2 is judged not to exist in StepS102, the operation is terminated. In Step S104, when the position ofthe optical pickup 1 is in the information area A2 where the track ofthe optical disk medium 2 exists, a collected laser beam spot goes intothe track cross state due to eccentricity of the optical disk medium 2or the deviation of the center at mounting or the like. However, whenthe position of the optical pickup 1 is in the mirror surface areas A30and A31 where the track of the optical disk medium 2 does not exist, theTE signal is not of an almost sine wave form as shown in FIG. 17 but ina constant level because tracks are not crossed, while the focus controlis operated normally.

[0070] Next, signal amplitude of the TE signal before adjustment isdetected by the signal amplitude detecting circuit 17 (Step S105), thedetected signal TEpp is compared with a prescribed amplitude signallevel TEref, which is set approximately to a level of noise on the TEsignal generated by defects on the mirror surface part of the opticaldisk medium 2 or the like, by the comparator 18, and whether the signalTEpp is equal to or larger than the prescribed amplitude or not isjudged (Step S106). When it is equal to or larger than the prescribedamplitude as the result of the judgement, the comparator 18 outputs highlevel “1” for the output signal Sig1 and the processing proceeds to StepS108. On the other hand, when it is under the prescribed amplitude asthe result in Step S106, the comparator 18 outputs low level “0” for theoutput signal Sig1 and the processing proceeds to Step S107. In StepS108, when the signal Sig1 is “1”, the MPU 6 judges the optical pickup 1is in the information area A2 where the track of the optical disk medium2 exists and is in a normal track cross state, and adjusts a next trackerror signal (Step S108). On the other hand, in Step S107, when thesignal Sig1 is “0”, the MPU 6 judges the optical pickup 1 is in themirror surface areas A30 and A31 where the track of the optical diskmedium 2 does not exist and is not in a normal track cross state,performs the operation for initializing the position of the opticalpickup 1, and adjusts the TE signal after the optical pickup 1 is movedto the information area A2 where the track of the optical disk medium 2exists (Step S108). To initialize the position of the optical pickup 1,however, the focus control is turned OFF first and is finally turned ONagain.

[0071] When the tracking control is prepared to be operated accuratelyby the adjustment of the TE signal in Step S108, the tracking control isturned ON next (Step S109), and a traverse following control issubsequently turned ON so that the laser 1beam spot of the opticalpickup 1 follows the spiral track on the optical disk medium 2 (StepS110). Thus, the laser beam spot of the optical pickup 1 can accuratelyfollow the track on the optical disk medium 2, thereby reproducinginformation in the optical disk medium 2 (Step 111).

[0072] As described above, in the optical disk apparatus according tothe first embodiment, the movement of the optical pickup 1 to theinitialized position at start-up is executed only when the opticalpickup 1 at start-up is in an area other than the information area A2where the track on the optical disk medium 2 exists, whereby thestart-up time can be drastically shorten in most cases.

[0073] While, in the first embodiment, in order to construct anamplitude detecting means for detecting amplitude of the TE signal and ameans for comparing with a previously set value, the signal amplitudedetecting circuit 17 and the comparator 18 are added to the conventionaloptical disk apparatus shown in FIG. 14, while this first embodiment maybe also realized without adding the signal amplitude detecting circuit17 and the comparator 18, by sampling the TEA signal in the MPU 6 withan initial value given to the adjusting circuit 7 and realizing theamplitude detecting means for detecting amplitude of the TE signal andthe means for comparing with a previously set value in the MPU 6.

EMBODIMENT 2

[0074]FIG. 3 is a block diagram illustrating a constitution of anoptical disk apparatus according to a second embodiment of the presentinvention.

[0075] In FIG. 3, numeral 19 denotes an adder which adds an outputsignal Sig2 of the MPU 6 and an output signal TRO of the trackingcontrol circuit 8 to output to the tracking driving circuit 9, so that atracking actuator of the optical pickup 1 is driven. The adder 19 canforcibly shift an objective lens of the optical pickup 1 in a radialdirection of the optical disk medium 2 by the output signal Sig2 of theMPU 6. Other same component parts as those shown in FIG. 1 are denotedby the same reference numerals, and their descriptions will be omitted.

[0076] Next, the operation of the optical disk apparatus according tothe second embodiment will be described.

[0077]FIG. 4 is a flow chart for explaining the operation of the opticaldisk apparatus according to the second embodiment of the presentinvention.

[0078] When the optical disk medium 2 is mounted on the optical diskapparatus or the power of the optical disk apparatus is turned ON (StepS201), a judgement whether the optical disk medium 2 is in the opticaldisk apparatus or not is performed (Step S202). A method of judgingwhether the optical disk medium 2 is in the optical disk apparatus ornot is one by means of the level of the RF signal and inertia asdescribed in the first embodiment, and its description will be omitted.When the optical disk medium 2 is judge to exist as the result of thejudgement in Step S202, the spindle motor 16 is driven to start rotatingthe optical disk medium 2 (Step S203), and the focus control of theoptical pickup 1 is turned ON (Step S204). On the other hand, when theoptical disk medium 2 is judged not to exist as the result of thejudgement in Step S202, the operation is terminated. In Step S204, whenthe position of the optical pickup 1 is in the information area A2 wherethe track of the optical disk medium 2 exists as shown in FIG. 16, acollected laser beam spot goes into track cross state as shown in FIG.17 due to eccentricity of the optical disk medium 2 or the deviation ofthe center at mounting or the like. On the other hand, when the positionof the optical pickup 1 is in the mirror surface areas A30 and A31 wherethe track of the optical disk medium 2 does not exist as shown in FIG.16, the TE signal is not of an almost sine wave form as shown in FIG. 17but in a constant level because tracks are not crossed, while the focuscontrol is operated normally.

[0079] Subsequently, the MPU 6 shifts the objective lens of the opticalpickup 1 to the outer periphery side of the optical disk medium 2 by theoutput signal Sig2 (Step S205). In this state, signal amplitude of theTE signal before adjustment is detected by the signal amplitudedetecting circuit 17 (Step S206), and the detected output signal TEpp iscompared with a prescribed amplitude signal level TEref by thecomparator 18. The prescribed amplitude signal level TEref is setapproximately to a level of noise on the TE signal generated by defectson the mirror surface part of the optical disk medium 2 or the like. Asthe result of the comparison in the comparator 18, when the outputsignal TEpp is equal to or larger than the prescribed amplitude signallevel TEref, the comparator 18 outputs high level “1” as the outputsignal Sig1, while, when the output signal TEpp is under the prescribedamplitude signal level TEref, the comparator 18 outputs low level “0” asthe output signal Sig1. The MPU 6 holds this detected value as avariable a (Step S207).

[0080] Next, the MPU 6 shifts the objective lens of the optical pickup 1to the inner periphery side of the optical disk medium 2 by the outputsignal Sig2 (Step S208). In this state, signal amplitude of the TEsignal before adjustment is detected by the signal amplitude detectingcircuit 17 (Step S209), and the detected signal TEpp is compared with aprescribed amplitude signal level TEref, which is set approximately to alevel of noise on the TE signal generated by defects on the mirrorsurface part of the optical disk medium 2 or the like, by the comparator18. As the result of the comparison in the comparator 18, when theoutput signal TEpp is equal to or larger than the prescribed amplitudesignal level TEref, the comparator 18 outputs high level “1” as theoutput signal Sig1, while, when the output signal TEpp is under theprescribed amplitude signal level TEref, the comparator 18 outputs lowlevel “0 ” as the output signal Sig1. The MPU 6 holds this detectedvalue as a variable B (Step S210) and cancels the shift of the objectivelens (Step S211).

[0081] When the optical pickup 1 is located either at a boundaryposition P0 which is a boundary between the information area A2 wherethe track of the optical disk medium 2 exists and the mirror surfacearea A30 where no track exists or at a boundary position P1 which is aboundary between the information area A2 where the track exists and themirror surface area A31, as shown in FIG. 16, a laser beam of theoptical pickup 1 crosses the boundary position P0 or boundary positionP1 of the optical disk medium 2 due to eccentricity of the optical diskmedium 2 or the deviation of the center at mounting or the like. Sincethe TE signal is not of an almost sine wave form but in a constant levelwhen the laser beam goes into the mirror surface part, there is thepossibility that amplitude of the original TE signal cannot be detectedand an appropriate gain may not be set by the variable gain amplifier 72that constructs the adjusting circuit 7, when the TE signal is adjustedat this position. Here, the above-described outer periphery shift amountand inner periphery shift amount of the objective lens are set largerthan the amount of eccentricity and deviation generated by eccentricityof the optical disk medium 2 or the deviation of the center at mounting,whereby the amplitude of the TE signal before adjustment is detected attwo positions beyond a range of an area where the track cross state isuncertain, and the detection result of comparing the two detected valuesof variable α and variable β with previously set prescribed amplitudecan be obtained. Thus, it is possible to judge more detailed positionsof the optical pickup 1 and of the optical disk medium 2 by the variableα and variable β as the detected values.

[0082] Subsequently, it is judged whether the detected values are α=“1”as well as β=“1” or not in step S212. When α=“1” as well as β=“1” as theresult of the judgement, the optical pickup 1 is entirely located insidethe information area A2, and a certain track cross state can beobtained, whereby the TE signal is adjusted at this position (StepS218). On the other hand, when the detected values are not α=“1” as wellas β=“1” in Step S212, it is judged whether α=“1” as well as β=“0” ornot (Step S213). When the detected values are α=“1” as well as β=0” asthe result of the judgement, the optical pickup 1 is located at theboundary position P0 between the information area A2 and the mirrorsurface area A30 where no track exists because track cross state cannotbe obtained when the objective lens is shifted to the inner peripheryside. Then, the optical pickup 1 is slightly moved to the outerperiphery side so that a certain track cross state can be obtained (StepS214), and the TE signal is adjusted. On the other hand, when thedetected values are not α=“1” as well as β=“0 38 in Step S213, it isjudged whether the detected values are α=“0” as well as β=“1” or not(Step S215). When the detected values are α=“0” as well as β=“1” as theresult of the judgement, the optical pickup 1 is located at the boundaryposition P1 between the information area A2 and the mirror surface areaA31 where no track exists because track cross state cannot be obtainedwhen the objective lens is shifted to the outer periphery side. Then,the optical pickup 1 is slightly moved to the inner periphery side sothat a certain track cross state is obtained (Step S216), and the trackerror signal is adjusted. On the other hand, when the detected valuesare not α=“0” as well as β=“1” in Step S215, which means they are α=“0”as well as β=“0”, the optical pickup 1 is entirely located inside themirror surface areas A30 or A31, and the operation for initializing theposition of the optical pickup 1 is performed (Step S217).

[0083] After the optical pickup 1 is moved to the information area A2where the track of the optical disk medium 2 exists in theabove-described Steps S212˜S217, the TE signal is adjusted (Step S218).The focus control is turned OFF at the beginning of the positionalinitialization of the optical pickup 1 and the focus control is turnedON again after the operation of the positional initialization isterminated. Also, when the optical pickup 1 is located at a boundaryposition between the mirror surface area A30 and the substrate area A40or at a boundary position between mirror surface area A31 and thesubstrate area A41 in the optical disk medium 2 shown in FIG. 16, and anerror status is generated in the focus control by the above-describedouter periphery shift operation and inner periphery shift operation ofthe objective lens, the operation for initializing the position of theoptical pickup 1 is performed, and after the optical pickup 1 is movedto the information area A2 where the track of the optical disk medium 2exists, and the TE signal is adjusted.

[0084] Next, since the tracking control is prepared to be operatedaccurately by the adjustment of the TE signal, the tracking control isturned ON (Step S219), and the traverse following control issubsequently turned ON so that the laser beam spot of the optical pickup1 follows the spiral track on the optical disk medium 2 (Step S220). Bythis operation, the laser beam spot of the optical pickup 1 canaccurately follow the track on the optical disk medium 2, wherebyinformation in the optical disk medium 2 can be reproduced (Step S221).

[0085] As described above, in the optical disk apparatus according tothe second embodiment, amplitude of the TE signal before adjustment isdetected, two detected values (variables α and β) are compared withpreviously set prescribed amplitude, it is judged from the result of thecomparison whether the optical pickup 1 is located entirely inside thearea where the track on the optical disk medium 2 exists, it is locatedat an end on the outer periphery side of the area where the trackexists, it is located at an end on the inner periphery side of the areawhere the track exists, or it is located entirely outside the area wherethe track exists, so as to decide whether the optical pickup needs to bemoved before the adjusting operation of the TE signal is performed, andthe optical pickup 1 can be moved to the most appropriate direction alsowhen the movement is judged to be required, whereby the movement of theoptical pickup 1 can be optimized even when the optical pickup 1 islocated at a boundary of the area where the track on the optical diskmedium 2 exists at startup, resulting in drastic reduction of a startuptime.

[0086] While, in the second embodiment, in order to construct anamplitude detecting means for detecting amplitude of the TE signal and ameans for comparing with a previously set value, the signal amplitudedetecting circuit 17 and the comparator 18 are added to the conventionaloptical disk apparatus shown in FIG. 14, while this second embodimentmay be also realized without adding the signal amplitude detectingcircuit 17 and the comparator 18, by sampling the TEA signal in the MPU6 with an initial value given to the adjusting circuit 7 and realizingthe amplitude detecting means for detecting amplitude of the TE signaland the means for comparing with a previously set value in the MPU 6.

EMBODIMENT 3

[0087]FIG. 3 is a block diagram illustrating a constitution of anoptical disk apparatus according to a third embodiment of the presentinvention. Respective constitutions in the figure are described in thesecond embodiment, and their descriptions will be omitted.

[0088] Next, the operation of the optical disk apparatus according tothe third embodiment will be described.

[0089]FIG. 5 is a flow chart for explaining the operation of the opticaldisk apparatus according to the third embodiment of the presentinvention.

[0090] When the optical disk medium 2 is mounted on the optical diskapparatus or the power of the optical disk apparatus is turned ON (StepS301), a judgement whether the optical disk medium 2 is in the opticaldisk apparatus or not is performed (Step S302). A method of judgingwhether the optical disk medium 2 is in the optical disk apparatus ornot is one by means of the level of the RF signal and inertia asdescribed in the first embodiment, and its description will be omitted.When the optical disk medium 2 is judged to exist as the result of thejudgement in Step S302, the spindle motor 16 is driven to start rotatingthe optical disk medium 2 (Step S303), and the optical pickup 1 isslightly moved in an outer periphery direction of the optical diskmedium 2 (Step S304). The amount of the movement then in an outerperiphery direction is one from a limit position of the movable range inwhich the optical pickup 1 can move to the inner periphery side up toentering the information area A2 of the optical disk medium 2 in whichtracks are present. When the position of the optical pickup 1 is in theinformation area A2 where the track of the optical disk medium 2 existsas shown in FIG. 16, a collected laser beam spot goes into track crossstate as shown in FIG. 17 due to eccentricity of the optical disk medium2 or the deviation of the center at mounting or the like. On the otherhand, when the position of the optical pickup 1 is in the mirror surfaceareas A30 and A31 where the track of the optical disk medium 2 does notexist as shown in FIG. 16, the TE signal is not of an almost sine waveform as shown in FIG. 17 but in a constant level because tracks are notcrossed, while the focus control is operated normally.

[0091] Subsequently, the MPU 6 shifts the objective lens of the opticalpickup 1 to the outer periphery side of the optical disk medium 2 by theoutput signal Sig2 (Step S305), and the focus control is turned ON (StepS306). At this time, when the optical pickup 1 is located on the outerperiphery side than the mirror surface area A31 at an outer peripherypart of the optical disk medium 2, and an error state is generated inthe focus control, a series of error processing operation as describedin the first embodiment that the operation for initializing the positionof the optical pickup 1 is performed and the TE signal is adjustedthereafter, which is not shown. Subsequently, when the optical pickup 1is in the information area A2 or the mirror surface area A31 and thefocus control is ON, signal amplitude of the TE signal is detected bythe signal amplitude detecting circuit 17 (Step S307). Then, thedetected output signal TEpp is compared with a prescribed amplitudesignal level TEref by the comparator 18, so that whether the outputsignal TEpp is equal to or larger than the prescribed amplitude signallevel TEref or not is judged (Step S308). The amplitude signal levelTEref is set approximately to a level of noise on the TE signalgenerated by defects on the mirror surface part of the optical diskmedium 2 or the like. As the result of the judgement in Step S308, whenthe output signal TEpp is equal to or larger than the prescribedamplitude signal level TEref, the comparator 18 outputs high level “1”as the output signal Sig1, and the processing proceeds to Step S310. Onthe other hand, as the result of the judgement in Step S308, when theoutput signal TEpp is under the prescribed amplitude signal level TEref,the comparator 18 outputs low level “0 ” as the output signal Sig1, andthe processing proceeds to Step S309.

[0092] Here, when the position of the optical pickup 1 is at theboundary position P1 between the information area A2 where the track ofthe optical disk medium 2 exists and the mirror surface area A31 whereno track exists as shown in FIG. 16, a laser beam of the optical pickup1 crosses the boundary position P1 of the optical disk medium 2 due toeccentricity of the optical disk medium 2 or the deviation of the centerat mounting or the like. Since the TE signal is not of an almost sinewave form but in a constant level when the laser beam goes into themirror surface part, there is the possibility that amplitude of theoriginal TE signal cannot be detected and an appropriate gain may not beset by the variable gain amplifier 72 that constructs the adjustingcircuit 7, when the TE signal is adjusted at this position. Here, theamount of shifting the objective lens to the outer periphery side is setlarger than the amount of eccentricity and deviation generated byeccentricity of the optical disk medium 2 or the deviation of the centerat mounting, whereby the laser beam is emitted to the outer peripheryside than an area where the track cross state is uncertain, and thus thelaser beam certainly goes into the mirror surface part A31 and thedetected signal Sig1 is low level “0”, and the optical pickup 1is-slightly moved to the inner periphery side of the optical disk medium2 so that the optical pickup 1 is certainly moved inside the informationarea A2 (Step S309). On the other hand, when the position of the opticalpickup 1 is slightly on the inner periphery side than the boundaryposition P1 between the information area A2 where the track of theoptical disk medium 2 exists and the mirror surface area A31 where notrack exists as shown in FIG. 16, the outer periphery shift of theobjective lens is next canceled in either judgement (Step 5310), whileamplitude of the TE signal is detected in a state where the track crossstate is uncertain since the objective lens of the optical pickup 1 isshifted to the outer periphery side as described above, whereby thelaser beam certainly goes into the information area A2.

[0093] After the optical pickup 1 is moved to the information area A2where the track of the optical disk medium 2 exists in theabove-described Steps S308 and S309, the TE signal is adjusted (StepS311). When the tracking control is prepared to be operated accuratelyby the adjustment of the TE signal in Step S311, the tracking control isturned ON next (Step S312), and the traverse control is subsequentlyturned ON so that the laser beam spot of the optical pickup 1 followsthe spiral track on the optical disk medium 2 (Step S313). By thisoperation, the laser beam spot of the optical pickup 1 can accuratelyfollow the track on the optical disk medium 2, whereby information inthe optical disk medium 2 can be reproduced (Step S314).

[0094] As described above, in the optical disk apparatus according tothe third embodiment, the amount of the optical pickup 1 moving atstartup can be drastically decreased, resulting in drastic reduction ofa startup time.

[0095] While, in the third embodiment, in order to construct anamplitude detecting means for detecting amplitude of the TE signal and ameans for comparing with a previously set value, the signal amplitudedetecting circuit 17 and the comparator 18 are added to the conventionaloptical disk apparatus shown in FIG. 14, while this third embodiment maybe also realized without the signal amplitude detecting circuit 17 andthe comparator 18 added, by sampling the TEA signal in the MPU 6 with aninitial value given to the adjusting circuit 7 and realizing theamplitude detecting means for detecting amplitude of the TE signal andthe means for comparing with a previously set value in the MPU 6.

EMBODIMENT 4

[0096]FIG. 3 is a block diagram illustrating a constitution of anoptical disk apparatus according to a fourth embodiment of the presentinvention. Respective constitutions in the figure are described in thesecond embodiment, and their descriptions will be omitted.

[0097] Next, the operation of the optical disk apparatus according tothe fourth embodiment will be described.

[0098]FIG. 6 is a flow chart for explaining the operation of the opticaldisk apparatus according to the fourth embodiment of the presentinvention.

[0099] When the optical disk medium 2 is mounted on the optical diskapparatus or the power of the optical disk apparatus is turned ON (StepS401), a judgement whether the optical disk medium 2 is in the opticaldisk apparatus or not is performed (Step S402). A method of judgingwhether the optical disk medium 2 is in the optical disk apparatus ornot is one by means of the level of the RF signal and inertia asdescribed in the first embodiment, and its description will be omitted.When the optical disk medium 2 is judged to exist as the result of thejudgement in Step S402, the spindle motor 16 is driven to start rotatingthe optical disk medium 2 (Step S403), and the optical pickup 1 isslightly moved in an inner periphery direction of the optical diskmedium 2 (Step S404). The amount of the movement then in an innerperiphery direction is one from a limit position of the movable range inwhich the optical pickup 1 can move to the outer periphery side up toentering the information area A2 of the optical disk medium 2 in whichtracks are present. Thus, the optical pickup 1 is located inside theinformation area A2 or on the inner periphery side than the informationarea A2 by the above-described operation.

[0100] Subsequently, the MPU 6 shifts the objective lens of the opticalpickup 1 to the inner periphery side of the optical disk medium 2 by theoutput signal Sig2 (Step S405), and the focus control is turned ON (StepS406). At this time, when the optical pickup 1 is located on the innerperiphery side than the mirror surface area A30 at an inner peripherypart of the optical disk medium 2, and an error state is generated inthe focus control, a series of error processing operation as describedin the first embodiment that the operation for initializing the positionof the optical pickup 1 is performed and the TE signal is adjustedthereafter, which is not shown. Subsequently, when the optical pickup 1is in the information area A2 or the mirror surface area A30 and thefocus control is ON, signal amplitude of the TE signal is detected bythe signal amplitude detecting circuit 17 (Step S407). Then, thedetected output signal TEpp is compared with a prescribed amplitudesignal level TEref by the comparator 18, so that whether the outputsignal TEpp is equal to or larger than the prescribed amplitude signallevel TEref or not is judged (Step S408). The amplitude signal levelTEref is set approximately to a level of noise on the TE signalgenerated by defects on the mirror surface part of the optical diskmedium 2 or the like. As the result of the judgement in Step S408, whenthe output signal TEpp is equal to or larger than the prescribedamplitude signal level TEref, the comparator 18 outputs high level “1”as the output signal Sig1, and the processing proceeds to Step S410. Onthe other hand, as the result of the judgement in Step S408, when theoutput signal TEpp is under the prescribed amplitude signal level TEref,the comparator 18 outputs low level “0” as the output signal Sig1, andthe processing proceeds to Step S409.

[0101] Here, when the position of the optical pickup 1 is at theboundary position P0 between the information area A2 where the track ofthe optical disk medium 2 exists and the mirror surface area A30 whereno track exists as shown in FIG. 16, a laser beam of the optical pickup1 crosses the boundary position P0 of the optical disk medium 2 due toeccentricity of the optical disk medium 2 or the deviation of the centerat mounting or the like. Since the TE signal is not of an almost sinewave form but in a constant level when the laser beam goes into themirror surface part, there is the possibility that amplitude of theoriginal TE signal cannot be detected and an appropriate gain may not beset by the variable gain amplifier 72 that constructs the adjustingcircuit 7, when the TE signal is adjusted at this position. Here, theamount of shifting the objective lens to the inner periphery side is setlarger than the amount of eccentricity and deviation generated byeccentricity of the optical disk medium 2 or the deviation of the centerat mounting, whereby the laser beam is emitted to the inner peripheryside than an area where the track cross state is uncertain, and thus thelaser beam certainly goes into the mirror surface part A30 and thedetected signal Sig1 is low level “0”, and the optical pickup 1 isslightly moved to the outer periphery side so that the optical pickup 1is certainly moved inside the information area A2 (Step S409). On theother hand, when the position of the optical pickup 1 is slightly on theouter periphery side than the boundary position P0 between theinformation area A2 where the track of the optical disk medium 2 existsand the mirror surface area A30 where no track exists as shown in FIG.16, the inner periphery shift of the objective lens is next canceled ineither judgement (Step S410), while amplitude of the TE signal isdetected in a state where the track cross state is uncertain since theobjective lens of the optical pickup 1 is shifted to the inner peripheryside as described above, whereby the laser beam certainly goes into theinformation area A2.

[0102] After the optical pickup 1 is moved to the information area A2where the track of the optical disk medium 2 exists in theabove-described Steps S408 and S409, the TE signal is adjusted (StepS411). When the tracking control is prepared to be operated accuratelyby the adjustment of the TE signal in Step S411, the tracking control isturned ON next (Step S412), and the traverse following control issubsequently turned ON so that the laser beam spot of the optical pickup1 follows the spiral track on the optical disk medium 2 (Step S413). Bythis operation, the laser beam spot of the optical pickup 1 canaccurately follow the track on the optical disk medium 2, wherebyinformation in the optical disk medium 2 can be reproduced (Step S414).

[0103] As described above, in the optical disk apparatus according tothe fourth embodiment, the amount of the optical pickup 1 moving atstartup can be drastically decreased, resulting in drastic reduction ofa startup time.

[0104] While, in the fourth embodiment, in order to construct anamplitude detecting means for detecting amplitude of the TE signal and ameans for comparing with a previously set value, the signal amplitudedetecting circuit 17 and the comparator 18 are added to the conventionaloptical disk apparatus shown in FIG. 14, while this fourth embodimentmay be also realized without adding the signal amplitude detectingcircuit 17 and the comparator 18, by sampling the TEA signal in the MPU6 with an initial value given to the adjusting circuit 7 and realizingthe amplitude detecting means for detecting amplitude of the TE signaland the means for comparing with a previously set value in the MPU 6.

EMBODIMENT 5

[0105]FIG. 17 is a diagram illustrating a TE signal and TEA signal intrack cross state, and also illustrates a period for which amplitude ofthe TE signal before adjustment is detected in an optical disk apparatusas defined in claim 5 of the present invention.

[0106] In a case where amplitude of the TE signal before adjustment isdetected for a period from t10 to t20 in FIG. 17(a) in theabove-described first to fourth embodiments of the present invention,the laser beam spot does not completely cross the track, resulting in anerror in the detection of the signal amplitude. On the other hand, whenthe amplitude of the TE signal before adjustment is detected for aperiod from t1 to t2 or more in FIG. 17(a), that is, the amplitude ofthe TE signal is detected for a period of one rotation or more insynchronization with the rotation of the optical disk medium 2, thelaser beam certainly crosses the track on the optical disk medium 2 dueto eccentricity of the optical disk medium 2, or eccentricity by thedeviation of the center at mounting and the like. Therefore, no error isgenerated in the detection of signal amplitude.

[0107] As described in the optical disk apparatus according to the fifthembodiment, amplitude of the TE signal is detected for a period of onerotation or more in synchronization with the rotation of the opticaldisk medium, whereby the amplitude of the TE signal can be certainlydetected.

EMBODIMENT 6

[0108]FIG. 7 is a block diagram illustrating a constitution of anoptical disk apparatus according to a sixth embodiment of the presentinvention.

[0109] In FIG. 7, numeral 17 denotes a signal amplitude detectingcircuit which is a means for detecting amplitude of the RF signalrepresenting a returned light quantity signal from the optical diskmedium 2, which outputs an output signal RFpp. Further, the signalamplitude detecting circuit 17 comprises a peak hold circuit, bottomhold circuit, and a differential amplifier (all not shown). Numeral 18denotes a comparator which compares the level of the output signal RFppoutputted from the signal amplitude detecting circuit 17 with aprescribed level signal RFref set by the MPU 6, and has its outputsignal Sig1 of the the comparator 18 inputted to the MPU 6. Other samecomponent parts as those shown in FIG. 1 are denoted by the samereference numerals, and their descriptions will be omitted.

[0110] Next, the operation of the optical disk apparatus according tothe sixth embodiment will be described.

[0111]FIG. 8 is a flow chart for explaining the operation of the opticaldisk apparatus according to the sixth embodiment of the presentinvention.

[0112] When the optical disk medium 2 is mounted on the optical diskapparatus or the power of the optical disk apparatus is turned ON (StepS501), a judgement whether the optical disk medium 2 is in the opticaldisk apparatus or not is performed (Step S502). A method of judgingwhether the optical disk medium 2 is in the optical disk apparatus ornot is one by means of the level of the RF signal and inertia asdescribed in the first embodiment, and its description will be omitted.When the optical disk medium 2 is judge to exist as the result of thejudgement in Step S502, the spindle motor 16 is driven to start rotatingthe optical disk medium 2 (Step S503), and the focus control of theoptical pickup 1 is turned ON (Step S504). At this time, when theposition of the optical pickup 1 is in the information area A2 where thetrack of the optical disk medium 2 exists as shown in FIG. 16, acollected laser beam spot, the track error signal, goes into track crossstate as shown in FIG. 17 due to eccentricity of the optical disk medium2 or the deviation of the center at mounting or the like. On the otherhand, when the position of the optical pickup 1 is in the mirror surfaceareas A30 and A31 where the track of the optical disk medium 2 does notexist as shown in FIG. 16, the TE signal is not of an almost sine waveform as shown in FIG. 17 but in a constant level because tracks arecrossed, while the focus control is operated normally. In a case wherethe optical disk medium 2 is a recordable optical disk medium such as aCD-R or a CD-RW, an unrecorded area exists also in the information areawhere the track exists.

[0113] The RF signal and TE signal in a recorded part and unrecordedpart in the track cross state are described in FIG. 9.

[0114] In the recorded part, since the track on the optical disk medium2 is recorded with reflectance being modulated, large amplitude isobtained for the signal amplitude of the RF signal (see FIG. 9(a)). Inthe unrecorded part, since the track on the optical disk medium 2 hasthe reflectance that is not modulated, a small amplitude is obtained forthe signal amplitude of the RF signal (see FIG. 9(c)). However, signalamplitude of the TE signal in the unrecorded part (See FIG. 9(d)) islarger than signal amplitude of the TE signal in the recorded part (SeeFIG. 9(b)). There exists the optical disk medium 2 having the signalamplitude of the TE signal in the unrecorded part which is almost twiceas large as the signal amplitude in the recorded part. Here, in a casewhere the optical disk apparatus according to the present invention is areproduce-only apparatus which only performs reproduction from theoptical disk medium 2, there is no need to turn the tracking control ONin the unrecorded part of the optical disk medium, and therefore it ispreferable that gain adjustment of the TE signal is performed in therecorded part.

[0115] Subsequently, after the focus control is turned ON in Step S504,the signal amplitude of the RF signal is detected by the signalamplitude detecting circuit 17 (Step S505). Then, the detected outputsignal RFpp is compared with a prescribed amplitude signal level RFrefby the comparator 18, so that whether the output signal RFpp is equal toor larger than the prescribed signal amplitude level RFref or not isjudged (Step S506). The amplitude signal level RFref is set larger thanthe level of the RF signal amplitude detected in the unrecorded part ofthe optical disk medium 2. As the result of the judgement in Step S506,when the output signal RFpp is equal to or larger than the prescribedamplitude signal level RFref, the comparator 18 outputs high level “1”as the output signal Sig1, and the processing proceeds to Step S508. Onthe other hand, as the result of the judgement in Step S506, when theoutput signal RFpp is under the prescribed amplitude signal level RFref,the comparator 18 outputs low level “0” as the output signal Sig1, andthe processing proceeds to Step S507. Thus, when the output signal Sig1is “1”, the MPU 6 judges the optical pickup 1 is in the recorded part ofthe information area A2 where the track of the optical disk medium 2exists and is in a normal track cross state, and adjusts a next trackerror signal (Step S108), while, when the signal Sig1 is “0” , the MPU 6judges the optical pickup 1 is in the unrecorded part of the informationarea A2 where the track of the optical disk medium 2 exists or in themirror surface areas A30 and A31 and is not in a normal track crossstate, and performs the operation for initializing the position of theoptical pickup (Step 507), and then adjusts the TE signal (Step S508).The focus control is turned OFF at the beginning of the positionalinitialization of the optical pickup 1 and the focus control is turnedON again at the end of the positional initialization setting.

[0116] Since the tracking control is prepared to be operated accuratelyby the adjustment of the TE signal in Step S508, the tracking control isturned ON next (Step S509), and a traverse following control issubsequently turned ON so that the laser beam spot of the optical pickup1 follows the spiral track on the optical disk medium 2 (Step S510).Thus, the laser beam spot of the optical pickup 1 can accurately followthe track on the optical disk medium 1, thereby reproducing informationon the optical disk medium 2 (Step S511).

[0117] As described above, in the optical disk apparatus according tothe sixth embodiment, the movement of the optical pickup 1 to theinitialized position at start-up is not performed when the opticalpickup 1 at start-up is located in the recorded area of the informationarea A2 where the track on the optical disk medium 2 exists, whereby thestart-up time can be drastically shorten in most cases.

[0118] While, in the sixth embodiment, in order to construct anamplitude detecting means for detecting amplitude of the TE signal and ameans for comparing with a previously set value, the signal amplitudedetecting circuit 17 and the comparator 18 are added to the conventionaloptical disk apparatus shown in FIG. 14, while this sixth embodiment maybe also realized without adding the signal amplitude detecting circuit17 and the comparator 18, by sampling the TEA signal in the MPU 6 withan initial value given to the adjusting circuit 7 and realizing theamplitude detecting means for detecting amplitude of the TE signal andthe means for comparing with a previously set value in the MPU 6.

EMBODIMENT 7

[0119]FIG. 10 is a block diagram illustrating a constitution of anoptical disk apparatus according to a seventh embodiment of the presentinvention.

[0120] In FIG. 10, numeral 19 denotes an adder which adds an outputsignal Sig2 of the MPU 6 and an output signal TRO of the trackingcontrol circuit 8 for driving a tracking actuator of the optical pickup1 by the tracking driving circuit 9. The adder 19 can forcibly shift anobjective lens of the optical pickup 1 in a radial direction of theoptical disk medium 2 by the output signal Sig2 of the MPU 6. Other samecomponent parts as those shown in FIG. 7 are denoted by the samereference numerals, and their descriptions will be omitted.

[0121] Next, the operation of the optical disk apparatus according tothe seventh embodiment will be described.

[0122]FIG. 11 is a flow chart for explaining the operation of theoptical disk apparatus according to the seventh embodiment of thepresent invention.

[0123] When the optical disk medium 2 is mounted on the optical diskapparatus or the power of the optical disk apparatus is turned ON (StepS601), a judgement whether the optical disk medium 2 is in the opticaldisk apparatus or not is performed (Step S602). A method of judgingwhether the optical disk medium 2 is in the optical disk apparatus ornot is one by means of the level of the RF signal and inertia asdescribed in the first embodiment, and its description will be omitted.When the optical disk medium 2 is judge to exist as the result of thejudgement in Step S602, the spindle motor 16 is driven to start rotatingthe optical disk medium 2 (Step S603), and the focus control of theoptical pickup 1 is turned ON (Step S604). On the other hand, when theoptical disk medium 2 is judged not to exist as the result of thejudgement in Step S602, the operation is terminated. In Step S604, whenthe position of the optical pickup 1 is in the information area A2 wherethe track of the optical disk medium 2 exists as shown in FIG. 16 withthe focus control of the optical pickup 1 ON, a collected laser beamspot goes into track cross state as shown in FIG. 17 due to eccentricityof the optical disk medium 2 or the deviation of the center at mountingor the like. On the other hand, when the position of the optical pickup1 is in the mirror surface areas A30 and A31 where the track of theoptical disk medium 2 does not exist as shown in FIG. 16, the TE signalis not of an almost sine wave form as shown in FIG. 17 but in a constantlevel because tracks are not crossed, while the focus control isoperated normally. The RF signal amplitude and the TE signal amplitudehave different levels in the recorded part and unrecorded part in theinformation area A2 as shown in FIG. 9.

[0124] Subsequently, the MPU 6 shifts the objective lens of the opticalpickup 1 to the outer periphery side of the optical disk medium 2 by theoutput signal Sig2 (Step S605). In this state, signal amplitude of theRF signal is detected by the signal amplitude detecting circuit 17 (StepS606), and the detected signal RFpp is compared with a prescribedamplitude signal level RFref by the comparator 18. At the time, theprescribed amplitude signal level RFref is set larger than the level ofthe RF signal amplitude detected in the unrecorded part of the opticaldisk medium 2. As the result of the comparison in the comparator 18,when the output signal RFpp is equal to or larger than the prescribedamplitude signal level RFref, the comparator 18 outputs high level “1”as the output signal Sig1, while, when the output signal RFpp is underthe prescribed amplitude signal level RFref, the comparator 18 outputslow level “0” as the output signal Sig1. The MPU 6 holds this detectedvalue as a variable a (Step S607).

[0125] Next, the MPU 6 shifts the objective lens of the optical pickup 1to the inner periphery side of the optical disk medium 2 by the outputsignal Sig2 (Step S608). In this state, signal amplitude of the RFsignal is detected by the signal amplitude detecting circuit 17 (StepS609), and the detected signal RFpp is compared with a prescribedamplitude signal level RFref, which is set larger than the level of theRF signal amplitude detected in the unrecorded part of the optical diskmedium 2, by the comparator 18. As the result of the comparison in thecomparator 18, when the output signal RFpp is equal to or larger thanthe prescribed amplitude signal level RFref, the comparator 18 outputshigh level “1” as the output signal Sig1, while, when the output signalRFpp is under the prescribed amplitude signal level RFref, thecomparator 18 outputs low level “0” as the output signal Sig1. The MPU 6holds this detected value as a variable β (Step S610) and cancels theshift of the objective lens (Step S611).

[0126] When the optical pickup 1 is located either at a boundaryposition P0 as a boundary between the information area A2 where thetrack of the optical disk medium 2 exists and the mirror surface areaA30 where no track exists or at a boundary position P1 as a boundarybetween the information area A2 where the track exists and the mirrorsurface area A31, as shown in FIG. 16, a laser beam of the opticalpickup 1 crosses the boundary position P0 or boundary position P1 of theoptical disk medium 2 due to eccentricity of the optical disk medium 2or the deviation of the center at mounting or the like. Since the TEsignal is not of an almost sine wave form but in a constant level whenthe laser beam goes into the mirror surface part, there is thepossibility that amplitude of the original TE signal cannot be detectedand an appropriate gain may not be set by the variable gain amplifier 72that constructs the adjusting circuit 7, when the TE signal is adjustedat this position. Here, the above-described outer periphery shift amountand inner periphery shift amount of the objective lens are set largerthan the amount of eccentricity and deviation generated by eccentricityof the optical disk medium 2 or the deviation of the center at mounting,whereby the amplitude of the RF signal before adjustment is detected attwo positions beyond a range of an area where the track cross state isuncertain, and more detailed positions of the optical pickup 1 and ofthe optical disk medium 2 can be judged by the variable α and variable βas the detected values. In a case where the optical disk medium 2 is arecordable optical disk medium 1 such as a CD-R or a CD-RW, an areawhich can be judged by the variable α and variable β as the detectedvalues is the area of the recorded part and unrecorded part in theinformation area A2 of the optical disk medium 2, when the unrecordedpart exists in the information area A2 where the track exists.

[0127] Subsequently, it is judged whether the detected values are α=“1”as well as β=“1” or not in step S612. When the detected values are α=“1”as well as β=“1” as the result of the judgement, the optical pickup 1 isentirely located in the recorded part of the information area A2, and acertain track cross state can be obtained, whereby the TE signal isadjusted at this position (Step S618). On the other hand, when thedetected values are not α=“1” as well as β=“1” in Step S612, it isjudged whether the detected values are α=“1” as well as β=“0” or not(Step S613). When the detected values are α=“1” as well as β=“0” as theresult of the judgement, the optical pickup 1 is located at a boundaryposition between the recorded part and the unrecorded part because theRF signal amplitude level is not obtained when the objective lens isshifted to the inner periphery side. Then, the optical pickup 1 isslightly moved to the outer periphery side so that a certain track crossstate is obtained (Step S614), and the TE signal is adjusted. On theother hand, when the detected values are not α=“1” as well as β=“0” inStep S613, it is judged whether the detected values are α=“0” as well asβ=“1” or not (Step S615). When the detected values are α=“0” as well asβ=“1” as the result of the judgement, the optical pickup 1 is located ata boundary position between the recorded part and the unrecorded partbecause the RF signal amplitude level is not obtained when the objectivelens is shifted to the outer periphery side. Then, the optical pickup 1is slightly moved to the inner periphery side so that a certain trackcross state is obtained (Step S616), and the TE signal is adjusted. Onthe other hand, when the detected values are not α=“0” as well as β=“1”in Step S615, which means they are α=“0” as well as β=“0”, the opticalpickup 1 is located in a part other than the recorded area, and theoperation for initializing the position of the optical pickup 1 isperformed (Step S617).

[0128] After the optical pickup 1 is moved to the information area A2where the track of the optical disk medium 2 exists in theabove-described Steps S612 to S617, the TE signal is adjusted (StepS618). The focus control is turned OFF at the beginning of thepositional initialization of the optical pickup 1 and the focus controlis turned ON again after the operation of the positional initializationis terminated. Also, when the optical pickup 1 is located at a boundaryposition between the mirror surface area A30 and the substrate area A40or at a boundary position between mirror surface area A31 and thesubstrate area A41 in the optical medium 2 as shown in FIG. 16, and anerror status is generated in the focus control by the above-describedouter periphery shift operation and inner periphery shift operation ofthe objective lens, the operation for initializing the position of theoptical pickup 1 is performed to move the optical pickup 1 to theinformation area A2 where the track of the optical disk medium 2 exists,and then the TE signal is adjusted (Step S218).

[0129] Next, since the tracking control is prepared to be operatedaccurately by the adjustment of the TE signal, the tracking control isturned ON (Step S619), and the traverse following control issubsequently turned ON so that the laser beam spot of the optical pickup1 follows the spiral track on the optical disk medium 2 (Step S620). Bythis operation, the laser beam spot of the optical pickup 1 canaccurately follow the track on the optical disk medium 2, wherebyinformation on the optical disk medium 2 can be reproduced (Step S621).

[0130] As described above, in the optical disk apparatus according tothe seventh embodiment, amplitude of the RF signal is detected, twodetected values (variables a and B) are compared with previously setprescribed amplitude, it is judged as the result of the comparisonwhether the optical pickup is located entirely in the recorded part inthe area where the track on the optical disk medium exists, it islocated at an end on the outer periphery side of the recorded part, itis located at an end on the inner periphery side of the recorded part,or it is located entirely outside the recorded part, so as to decidewhether the optical pickup needs to be moved before the adjustingoperation of the track error signal is performed or not, and the opticalpickup 1 can be moved to the most appropriate direction also when themovement is judged to be required, whereby the movement of the opticalpickup can be optimized at start-up, resulting in drastic reduction of astartup time.

[0131] While, in the seventh embodiment, in order to construct anamplitude detecting means for detecting amplitude of the TE signal and ameans for comparing with a previously set value, the signal amplitudedetecting circuit 17 and the comparator 18 are added to the conventionaloptical disk apparatus shown in FIG. 14, while this seventh embodimentmay be also realized without adding the signal amplitude detectingcircuit 17 and the comparator 18, by sampling the TEA signal in the MPU6 with an initial value given to the adjusting circuit 7 and realizingthe amplitude detecting means for detecting amplitude of the TE signaland the means for comparing with a previously set value in the MPU 6.

EMBODIMENT 8

[0132]FIG. 10 is a block diagram illustrating a constitution of anoptical disk apparatus according to an eighth embodiment of the presentinvention. Respective constitutions in the figure are described in theseventh embodiment, and their descriptions will be omitted.

[0133] Next, the operation of the optical disk apparatus according tothe eighth embodiment will be described.

[0134]FIG. 12 is a flow chart for explaining the operation of theoptical disk apparatus according to the eighth embodiment of the presentinvention.

[0135] When the optical disk medium 2 is mounted on the optical diskapparatus or the power of the optical disk apparatus is turned ON (StepS701), a judgement whether the optical disk medium 2 is in the opticaldisk apparatus or not is performed (Step S702). A method of judgingwhether the optical disk medium 2 is in the optical disk apparatus ornot is one by means of the level of the RF signal and inertia asdescribed in the first embodiment, and its description will be omitted.When the optical disk medium 2 is judged to exist as the result of thejudgement in Step S702, the spindle motor 16 is driven to start rotatingthe optical disk medium 2 (Step S703), and the optical pickup 1 isslightly moved in an outer periphery direction (Step 5704). The amountof the movement then in an outer periphery direction is one from a limitposition of the movable range in which the optical pickup 1 can move tothe inner periphery side up to entering the information area A2 of theoptical disk medium 2 in which the tracks are present. The opticalpickup 1 is located inside the information area A2 where the track ofthe optical disk medium 2 exists or on the outer periphery side than theinformation area A2 as shown in FIG. 16.

[0136] Subsequently, the MPU 6 shifts the objective lens of the opticalpickup 1 to the outer periphery side by the output signal Sig2 (StepS705), and the focus control is turned ON (Step S706). At this time,when the optical pickup 1 is located on the outer periphery side thanthe mirror surface area A31 at an outer periphery part of the opticaldisk medium 2, and an error state is generated in the focus control, aseries of error processing operation that the operation for initializingthe position of the optical pickup 1 is performed and the TE signal isadjusted thereafter, which is not shown. Subsequently, when the opticalpickup 1 is in the information area A2 or the mirror surface area A31and the focus control is ON, signal amplitude of the RF signal isdetected by the signal amplitude detecting circuit 17 (Step S707). Then,the detected output signal RFpp is compared with a prescribed amplitudesignal level RFref by the comparator 18, so that whether the outputsignal RFpp is equal to or larger than the prescribed amplitude signallevel RFref or not is judged (Step S708). The amplitude signal levelRFref is set larger than the level of the RF signal amplitude detectedin the unrecorded part of the optical disk medium 2. As the result ofthe judgement in Step S708, when the output signal RFpp is equal to orlarger than the prescribed amplitude signal level RFref, the comparator18 outputs high level “1” as the output signal Sig1, and the processingproceeds to Step S710. On the other hand, as the result of the judgementin Step S708, when the output signal RFpp is under the prescribedamplitude signal level RFref, the comparator 18 outputs low level “0” asthe output signal Sig1, and the processing proceeds to Step S709.

[0137] Here, when the position of the optical pickup 1 is at a boundarybetween the recorded part and the unrecorded part of the informationarea A2 where the track of the optical disk medium 2 exists as shown inFIG. 16, a laser beam of the optical pickup 1 crosses the boundaryposition P1 of the optical disk medium 2 due to eccentricity of theoptical disk medium 2 or the deviation of the center at mounting or thelike. When the laser beam goes into the unrecorded part, the TE signalhas larger amplitude than that in the recorded part, and thus, there isthe possibility that amplitude of the original TE signal cannot bedetected and an appropriate gain may not be set by the variable gainamplifier 72 that constructs the adjusting circuit 7, when the TE signalis adjusted at this position. Here, the amount of shifting the objectivelens to the outer periphery side is set larger than the amount ofeccentricity and deviation generated by eccentricity of the optical diskmedium 2 or the deviation of the center at mounting, whereby the laserbeam is emitted to the outer periphery side than an area where the trackcross state is uncertain, and thus the laser beam certainly goes intothe unrecorded part and the detected signal Sig1 is low level “0”, andthe optical pickup 1 is slightly moved to the inner periphery side sothat the optical pickup 1 is certainly moved inside the information areaA2 (Step S709). On the other hand, when the position of the opticalpickup 1 is slightly on the inner periphery side than the boundaryposition between the recorded part and the unrecorded part of theinformation area A2 where the track of the optical disk medium 2 existsas shown in FIG. 16, the outer periphery shift of the objective lens isnext canceled in either judgement (Step S710), while amplitude of the RFsignal is detected in a state where the track cross state is uncertainsince the objective lens of the optical pickup 1 is shifted to the outerperiphery side, whereby the laser beam certainly goes into the recordedarea of the information area A2.

[0138] After the outer periphery shift of the objective lens is canceledin Step S710, the TE signal is adjusted (Step S711). When the trackingcontrol is prepared to be operated accurately by the adjustment of theTE signal in Step S711, the tracking control is turned ON next (StepS712), and the traverse following control is subsequently turned ON sothat the laser beam spot of the optical pickup 1 follows the spiraltrack on the optical disk medium 2 (Step S713). Thus, the laser beamspot of the optical pickup 1 can accurately follow the track on theoptical disk medium 2, whereby information in the optical disk medium 2can be reproduced (Step S714).

[0139] As described above, in the optical disk apparatus according tothe eighth embodiment, the amount of the optical pickup moving atstartup can be drastically decreased, resulting in drastic reduction ofa startup time.

[0140] While, in the eighth embodiment, in order to construct anamplitude detecting means for detecting amplitude of the TE signal and ameans for comparing with a previously set value, the signal amplitudedetecting circuit 17 and the comparator 18 are added to the conventionaloptical disk apparatus shown in FIG. 14, while this eighth embodimentmay be also realized without adding the signal amplitude detectingcircuit 17 and the comparator 18, by sampling the TEA signal in the MPU6 with an initial value given to the adjusting circuit 7 and realizingthe amplitude detecting means for detecting amplitude of the TE signaland the means for comparing with a previously set value in the MPU 6.

EMBODIMENT 9

[0141]FIG. 10 is a block diagram illustrating a constitution of anoptical disk apparatus according to an ninth embodiment of the presentinvention. Respective constitutions in the figure are described in theseventh embodiment, and their descriptions will be omitted.

[0142] Next, the operation of the optical disk apparatus according tothe ninth embodiment will be described.

[0143]FIG. 13 is a flow chart for explaining the operation of theoptical disk apparatus according to the ninth embodiment of the presentinvention.

[0144] When the optical disk medium 2 is mounted on the optical diskapparatus or the power of the optical disk apparatus is turned ON (StepS801), a judgement whether the optical disk medium 2 is in the opticaldisk apparatus or not is performed (Step S802). A method of judgingwhether the optical disk medium 2 is in the optical disk apparatus ornot is one by means of the level of the RF signal and inertia asdescribed in the first embodiment, and its description will be omitted.When the optical disk medium 2 is judged to exist as the result of thejudgement in Step S802, the spindle motor 16 is driven to start rotatingthe optical disk medium 2 (Step S803), and the optical pickup 1 isslightly moved in an inner periphery direction (Step S804). The amountof the movement then in an inner periphery direction is one from a limitposition of the movable range in which the optical pickup 1 can move tothe outer periphery side up to entering the information area A2 of theoptical disk medium 2 in which tracks are present. Thus, the opticalpickup 1 is located inside the information area A2 or on the innerperiphery side than the information area A2 in FIG. 16 by theabove-described operation.

[0145] Subsequently, the MPU 6 shifts the objective lens of the opticalpickup 1 to the inner periphery side of the optical disk medium 2 by theoutput signal Sig2 (Step S805), and the focus control is turned ON (StepS806). At this time, when the optical pickup 1 is located on the innerperiphery side than the mirror surface area A30 at an inner peripherypart of the optical disk medium 2, and an error state is generated inthe focus control, a series of error processing operation that theoperation for initializing the position of the optical pickup 1 isperformed and the TE signal is adjusted thereafter, which is not shown.Subsequently, when the optical pickup 1 is in the information area A2 orthe mirror surface area A30 and the focus control is ON, signalamplitude of the RF signal is detected by the signal amplitude detectingcircuit 17 (Step S807). Then, the detected output signal RFpp iscompared with a prescribed amplitude signal level RFref by thecomparator 18, so that whether the output signal RFpp is equal to orlarger than the prescribed amplitude signal level RFref or not is judged(Step S808). The amplitude signal level RFref is set larger than thelevel of the RF signal amplitude detected in the unrecorded part of theoptical disk medium 2. As the result of the judgement in Step S808, whenthe output signal RFpp is equal to or larger than the prescribedamplitude signal level RFref, the comparator 18 outputs high level “1”as the output signal Sig1, and the processing proceeds to Step S810. Onthe other hand, as the result of the judgement in Step S808, when theoutput signal RFpp is under the prescribed amplitude signal level RFref,the comparator 18 outputs low level “0” as the output signal Sig1, andthe processing proceeds to Step S809.

[0146] Here, when the position of the optical pickup 1 is at a boundarybetween the recorded part and the unrecorded part of the informationarea A where the track of the optical disk medium 2 exists as shown inFIG. 16, a laser beam of the optical pickup 1 crosses the boundaryposition P0 of the optical disk medium 2 due to eccentricity of theoptical disk medium 2 or the deviation of the center at mounting or thelike. When the laser beam goes into the unrecorded part, the TE signalhas larger amplitude than that in the recorded part, and thus, there isthe possibility that amplitude of the TE signal in the recorded partwhich performs the original operation cannot be detected and anappropriate gain may not be set by the variable gain amplifier 72 thatconstructs the adjusting circuit 7, when the TE signal is adjusted atthis position. Here, the amount of shifting the objective lens to theinner periphery side is set larger than the amount of eccentricity anddeviation generated by eccentricity of the optical disk medium 2 or thedeviation of the center at mounting, whereby the laser beam is emittedto the outer periphery side than an area where the track cross state isuncertain, and thus the laser beam certainly goes into the unrecordedpart and the detected signal Sig1 is low level “0”, and the opticalpickup 1 is slightly moved to the outer periphery side of the opticaldisk medium 2 (Step S809), so that the optical pickup 1 is certainlymoved inside the information area A2. On the other hand, when theposition of the optical pickup 1 is slightly on the outer periphery sidethan the boundary position P0 between the recorded part and theunrecorded part of the information area A2 where the track of theoptical disk medium 2 exists as shown in FIG. 16, the inner peripheryshift of the objective lens is next canceled in either judgement (StepS810), while amplitude of the RF signal is detected in a state where thetrack cross state is uncertain since the objective lens of the opticalpickup 1 is shifted to the inner periphery side as described above,whereby the laser beam certainly goes into the information area A2.

[0147] After the optical pickup 1 is moved to the information area A2where the track of the optical disk medium 2 exists in theabove-described Steps S808 and S809, the TE signal is adjusted (StepS811). When the tracking control is prepared to be operated accuratelyby the adjustment of the TE signal in Step S811, the tracking control isturned ON next (Step S812), and the traverse following control issubsequently turned ON so that the laser beam spot of the optical pickup1 follows the spiral track on the optical disk medium 2 (Step S813).Thus, the laser beam spot of the optical pickup 1 can accurately followthe track on the optical disk medium 2, whereby information in theoptical disk medium 2 can be reproduced (Step S814).

[0148] As described above, in the optical disk apparatus according tothe ninth embodiment, the amount of the optical pickup moving at startupcan be drastically decreased, resulting in drastic reduction of astartup time.

[0149] While, in the ninth embodiment, in order to construct anamplitude detecting means for detecting amplitude of the TE signal and ameans for comparing with a previously set value, the signal amplitudedetecting circuit 17 and the comparator 18 are added to the conventionaloptical disk apparatus shown in FIG. 14, while this ninth embodiment maybe also realized without adding the signal amplitude detecting circuit17 and the comparator 18, by sampling the TEA signal in the MPU 6 withan initial value given to the adjusting circuit 7 and realizing theamplitude detecting means for detecting amplitude of the TE signal andthe means for comparing with a previously set value in the MPU 6.

EMBODIMENT 10

[0150]FIG. 9 is a diagram illustrating an RF signal and TE signal of arecorded part and unrecorded part in track cross state, which alsoillustrates a period for which amplitude of the RF signal is detected inan optical disk apparatus as defined in claim 10 of the presentinvention.

[0151] In a case where amplitude of the TE signal before adjustment isdetected for a period from t10 to t20 in FIG. 9 in the above-describedsixth to ninth embodiments, the laser beam spot does not completelycross the track, resulting in an error in the detection of the signalamplitude. On the other hand, when amplitude of the RF signal isdetected for a period from t1 to t2 or more in FIG. 9, that is, for aperiod of one rotation or more in synchronization with the rotation ofthe optical disk medium 2, the laser beam spot certainly crosses thetrack on the optical disk medium 2 due to eccentricity of the opticaldisk medium 2 or eccentricity by the deviation of the center at mountingor the like, whereby no error is generated in the detection of signalamplitude.

[0152] As described in the optical disk apparatus according to the tenthembodiment, amplitude of the RF signal is detected for a period of onerotation or more in synchronization with the rotation of the opticaldisk medium, whereby the amplitude of the track error signal can becertainly detected.

[0153] While the optical disk apparatus in the first to tenthembodiments is described taking an optical disk apparatus which onlyperforms reproduction of information for example, an optical diskapparatus such as CD-R or CD-RW, which also enables recording ofinformation can be also applied, thereby to achieve the same effects asthose in the embodiments.

APPLICABILITY IN INDUSTRY

[0154] As described above, an optical disk apparatus according to thepresent invention is suited to perform recording or reproduction ofinformation into/from an optical disk.

1. An optical disk apparatus which comprises: an optical pickup whichperforms recording or reproduction of information into/from an opticaldisk medium having a track for information recording; a focus controlmeans for controlling the optical pickup so as to focus a light beam onthe optical disk medium; a tracking actuator which drives the opticalpickup so that an irradiated position of the light beam follows thetrack for information recording; a track error detecting means fordetecting a deviation from the track position of the irradiated positionof the light beam; an adjusting means for adjusting gain and offset of atrack error signal outputted by the track error detecting means; and atracking driving means for driving the tracking actuator according to anoutput signal of the adjusting means, comprising: an amplitude detectingmeans for detecting amplitude of the track error signal; and a transfermeans for transferring the optical pickup in a radial direction of theoptical disk medium, wherein the focus control means focuses the lightbeam irradiated from the optical pickup onto the optical disk medium,and the adjusting means adjusts the gain and offset of the track errorsignal when the amplitude of the track error signal detected by theamplitude detecting means is equal to or larger than a previously setvalue, while the optical pickup is transferred to a previously decidedposition when the amplitude of the track error signal detected by theamplitude detecting means is under the previously set value.
 2. Anoptical disk apparatus which comprises: an optical pickup which performsrecording or reproduction of information into/from an optical diskmedium having a track for information recording; a focus control meansfor controlling the optical pickup so as to focus a light beam on theoptical disk medium; a tracking actuator which drives the optical pickupso that an irradiated position of the light beam follows the track forinformation recording; a track error detecting means for detecting adeviation from the track position of the irradiated position of thelight beam; an adjusting means for adjusting gain and offset of a trackerror signal outputted by the track error detecting means; and atracking driving means for driving the tracking actuator according to anoutput signal of the adjusting means, comprising: an amplitude detectingmeans for detecting amplitude of the track error signal; an objectivelens shift means for providing a signal to the tracking driving means toshift an objective lens of the optical pickup in a radial direction ofthe optical disk medium; and a transfer means for transferring theoptical pickup in the radial direction of the optical disk medium,wherein the focus control means focuses the light beam irradiated fromthe optical pickup onto the optical disk medium, and according to afirst comparison result which is obtained by comparing amplitude of afirst track error signal detected in the amplitude detecting means witha previously set value in a state where the objective lens of theoptical pickup is shifted in an outer periphery direction of the opticaldisk medium by the objective lens shift means, as well as a secondcomparison result which is obtained by comparing amplitude of a secondtrack error signal detected in the amplitude detecting means with thepreviously set value in a state where the objective lens of the opticalpickup is shifted in an inner periphery direction of the optical diskmedium by the objective lens shift means, the gain and offset of thetrack error signal are adjusted when the first and the second comparisonresults are both equal to or larger than the previously set value; theoptical pickup is transferred in the outer periphery direction of theoptical disk medium when the first comparison result is equal to orlarger than the previously set value and the second comparison result isunder the previously set value; the optical pickup is transferred in theinner periphery direction of the optical disk medium when the firstcomparison result is under the previously set value and the secondcomparison result is equal to or larger than the previously set value;and the optical pickup is transferred to a previously decided positionwhen the first and the second comparison results are both under thepreviously set value.
 3. An optical disk apparatus which comprises: anoptical pickup which performs recording or reproduction of informationinto/from an optical disk medium having a track for informationrecording; a focus control means for controlling the optical pickup soas to focus a light beam on the optical disk medium; a tracking actuatorwhich drives the optical pickup so that an irradiated position of thelight beam follows the track for information recording; a track errordetecting means for detecting a deviation from the track position of theirradiated position of the light beam; an adjusting means for adjustinggain and offset of a track error signal outputted by the track errordetecting means; and a tracking driving means for driving the trackingactuator according to an output signal of the adjusting means,comprising: an amplitude detecting means for detecting amplitude of thetrack error signal; an objective lens shift means for providing a signalto the tracking driving means to shift an objective lens of the opticalpickup in a radial direction of the optical disk medium; and a transfermeans for transferring the optical pickup in the radial direction of theoptical disk medium, wherein the transfer means transfers the opticalpickup in an outer periphery direction of the optical disk medium, thefocus control means focuses the light beam irradiated from the opticalpickup onto the optical disk medium, and shift of the objective lens isstopped and the adjusting means adjusts the gain and offset of the trackerror signal when the amplitude of the track error signal detected bythe amplitude detecting means is equal to or larger than a previouslyset value in a state where the objective lens of the optical pickup isshifted in the outer periphery direction of the optical disk medium bythe objective lens shift means, while the optical pickup is transferredin an inner periphery direction of the optical disk medium when theamplitude of the track error signal detected by the amplitude detectingmeans is under the previously set value.
 4. An optical disk apparatuswhich comprises: an optical pickup which performs recording orreproduction of information to an optical disk medium having a track forinformation recording; a focus control means for controlling the opticalpickup so as to focus a light beam on the optical disk medium; atracking actuator which drives the optical pickup so that an irradiatedposition of the light beam follows the track for information recording;a track error detecting means for detecting a deviation from the trackposition of the irradiated position of the light beam; an adjustingmeans for adjusting gain and offset of a track error signal outputted bythe track error detecting means; and a tracking driving means fordriving the tracking actuator according to an output signal of theadjusting means, comprising: an amplitude detecting means for detectingamplitude of the track error signal; an objective lens shift means forproviding a signal to the tracking driving means to shift an objectivelens of the optical pickup in a radial direction of the optical diskmedium; and a transfer means for transferring the optical pickup in theradial direction of the optical disk medium, wherein the transfer meanstransfers the optical pickup in an inner periphery direction of theoptical disk medium, the focus control means focuses the light beamirradiated from the optical pickup onto the optical disk medium, andshift of the objective lens is stopped and the gain and offset of thetrack error signal are adjusted by the adjusting means when theamplitude of the track error signal detected by the amplitude detectingmeans is equal to or larger than a previously set value in a state wherethe objective lens shift means shifts the objective lens of the opticalpickup in the inner periphery direction of the optical disk medium,while the optical pickup is transferred in an outer periphery directionof the optical disk medium when the amplitude of the track error signaldetected by the amplitude detecting means is under the previously setvalue.
 5. The optical disk apparatus as defined in any of claims 1 to 4,wherein the amplitude of the track error signal is detected by theamplitude detecting means for a period of one rotation or more insynchronization with the rotation of the optical disc medium.
 6. Anoptical disk apparatus which comprises: an optical pickup which performsrecording or reproduction of information into/from an optical diskmedium having a track for information recording; a focus control meansfor controlling the optical pickup so as to focus a light beam on theoptical disk medium; a tracking actuator which drives the optical pickupso that an irradiated position of the light beam follows the track forinformation recording; a track error detecting means for detecting adeviation from the track position of the irradiated position of thelight beam; an adjusting means for adjusting gain and offset of a trackerror signal outputted by the track error detecting means; and atracking driving means for driving the tracking actuator according to anoutput signal of the adjusting means, comprising: a returned lightquantity detecting means for detecting a returned light quantity fromthe optical disk medium; an amplitude detecting means for detectingamplitude of an output signal of the returned light quantity detectingmeans; and a transfer means for transferring the optical pickup in aradial direction of the optical disk medium, wherein the focus controlmeans focuses the light beam from the optical pickup onto the opticaldisk medium, and the adjusting means adjusts the gain and offset of thetrack error signal when the amplitude of the returned light quantitysignal detected by the amplitude detecting means is equal to or largerthan a previously set value, while the optical pickup is transferred toa previously decided position when the amplitude of the returned lightquantity signal detected by the amplitude detecting means is under thepreviously set value.
 7. An optical disk apparatus which comprises: anoptical pickup which performs recording or reproduction of informationinto/from an optical disk medium having a track for informationrecording; a focus control means for controlling the optical pickup soas to focus a light beam on the optical disk medium; a tracking actuatorwhich drives the optical pickup so that an irradiated position of thelight beam follows the track for information recording; a track errordetecting means for detecting a deviation from the track position of theirradiated position of the light beam; an adjusting means for adjustinggain and offset of a track error signal outputted by the track errordetecting means; and a tracking driving means for driving the trackingactuator according to an output signal of the adjusting means,comprising; a returned light quantity detecting means for detecting areturned light quantity from the optical disk medium; an amplitudedetecting means for detecting amplitude of an output signal of thereturned light quantity detecting means; an objective lens shift meansfor providing a signal to the tracking driving means to shift anobjective lens of the optical pickup in a radial direction of theoptical disk medium; and a transfer means for transferring the opticalpickup in the radial direction of the optical disk medium, wherein thefocus control means focuses the light beam irradiated from the opticalpickup onto the optical disk medium, and according to a first comparisonresult which is obtained by comparing amplitude of a first returnedlight quantity signal detected in the amplitude detecting means with apreviously set value in a state where the objective lens of the opticalpickup is shifted in an outer periphery direction of the optical diskmedium by the objective lens shift means, as well as a second comparisonresult which is obtained by comparing amplitude of a second returnedlight quantity signal detected in the amplitude detecting means with thepreviously set value in a state where the objective lens of the opticalpickup is shifted in an inner periphery direction of the optical diskmedium by the objective lens shift means, the gain and offset of thetrack error signal are adjusted when the first and the second comparisonresults are both equal to or larger than the previously set value; theoptical pickup is transferred in the outer periphery direction of theoptical disk medium when the first comparison result is equal to orlarger than the previously set value and the second comparison result isunder the previously set value; the optical pickup is transferred in theinner periphery direction of the optical disk medium when the firstcomparison result is under the previously set value and the secondcomparison result is equal to or larger than the previously set value;and the optical pickup is transferred to a previously decided positionwhen the first and the second comparison results are both under thepreviously set value.
 8. An optical disk apparatus which comprises: anoptical pickup which performs recording or reproduction of informationinto/from an optical disk medium having a track for informationrecording; a focus control means for controlling the optical pickup soas to focus a light beam on the optical disk medium; a tracking actuatorwhich drives the optical pickup so that an irradiated position of thelight beam follows the track for information recording; a track errordetecting means for detecting a deviation from the track position of theirradiated position of the light beam; an adjusting means for adjustinggain and offset of a track error signal outputted by the track errordetecting means; and a tracking driving means for driving the trackingactuator according to an output signal of the adjusting means,comprising: a returned light quantity detecting means for detecting areturned light quantity from the optical disk medium; an amplitudedetecting means for detecting amplitude of an output signal of thereturned light quantity detecting means; an objective lens shift meansfor providing a signal to the tracking driving means to shift anobjective lens of the optical pickup in a radial direction of theoptical disk medium; and a transfer means for transferring the opticalpickup in the radial direction of the optical disk medium, wherein thetransfer means transfers the optical pickup in an outer peripherydirection of the optical disk medium, the focus control means focusesthe light beam from the optical pickup onto the optical disk medium, andshift of the objective lens is stopped and the gain and offset of thetrack error signal are adjusted by the adjusting means when theamplitude of the returned light quantity signal detected by theamplitude detecting means is equal to or larger than a previously setvalue in a state where the objective lens of the optical pickup isshifted in the outer periphery direction of the optical disk medium bythe objective lens shift means, while the optical pickup is transferredin an inner periphery direction of the optical disk medium when theamplitude of the returned light quantity signal detected by theamplitude detecting means is under the previously set value.
 9. Anoptical disk apparatus which comprises: an optical pickup which performsrecording or reproduction of information into/from an optical diskmedium having a track for information recording; a focus control meansfor controlling the optical pickup so as to focus a light beam on theoptical disk medium; a tracking actuator which drives the optical pickupso that an irradiated position of the light beam follows the track forinformation recording; a track error detecting means for detecting adeviation from the track position of the irradiated position of thelight beam; an adjusting means for adjusting gain and offset of a trackerror signal outputted by the track error detecting means; and atracking driving means for driving the tracking actuator according to anoutput signal of the adjusting means, comprising: a returned lightquantity detecting means for detecting a returned light quantity fromthe optical disk medium; an amplitude detecting means for detectingamplitude of an output signal of the returned light quantity detectingmeans; an objective lens shift means for providing a signal to thetracking driving means to shift an objective lens of the optical pickupin a radial direction of the optical disk medium; and a transfer meansfor transferring the optical pickup in the radial direction of theoptical disk medium, wherein the transfer means transfers the opticalpickup in an inner periphery direction of the optical disk medium, thelight beam irradiated from the optical pickup is focused onto theoptical disk medium by the focus control means, and shift of theobjective lens is stopped and the gain and offset of the track errorsignal are adjusted by the adjusting means when the amplitude of thereturned light quantity signal detected by the amplitude detecting meansis equal to or larger than a previously set value in a state where theobjective lens of the optical pickup is shifted in the inner peripherydirection of the optical disk medium by the objective lens shift means,while the optical pickup is transferred in an outer periphery directionof the optical disk medium when the amplitude of the returned lightquantity signal detected by the amplitude detecting means is under thepreviously set value. The optical disk apparatus as defined in any ofclaims 6 to 9, wherein the amplitude of the returned light quantitysignal is detected by the amplitude detecting means for a period of onerotation or more in synchronization with the rotation of the opticaldisk medium.